question bank-antenna wave and propogation

EC2353 ANTENNA AND WAVE PROPAGATION

DEPARTMENT OF ECE

ST.JOSEPH'S COLLEGE OF ENGINEERING ELECTRONICS AND COMMUNICATION ENGINEERING VI-SEM EC 2353-ANTENNA AND WAVE PROPAGATION QUESTION BANK UNIT-I ELECTROMAGNETIC ELECTROMAGNET IC RADIATION AND ANTENNA FUNDAMENTALS FUNDAMENTALS PART-A (2 Marks) 1.What is retarded potential?

If an alternating current is flowing in a short element, the effect of current is not felt instantaneously at a distant point, but only after some interval equal to the time required for the fields to propagate some distance. So the fields obtained after retardation time are known as retarded fields. They are very important in radiation calculation. 2. Define an alternating current element.

If ‘dl’ be the infinitesimal length of a short dipole, ‘I’ be the current then ‘I dl’ is called as the current element. Since this element generates alternating current it is called as alternating current element. 3.Distinguish between power and directive gains.

The power gain is the ratio of radiation Intensity in a given direction to the average total input power. But the directive gain is the ratio of Radiation Intensity in a specified direction to the Average radiation intensity. 4.Define directivity of an antenna?

It is the value of directive gain in the direction of its maximum value. It is the ratio of power radiated from the test antenna to the power radiated from the isotropic antenna. 5.What do you mean by effective aperture of an antenna?

An effective aperture is defined as the ratio of the power delivered to the load to the incident power density. 6.Distinguish between standing wave antennas and travelling wave antennas?

Linear antennas that exhibit current and voltage standing wave patterns formed by reflections from the open end of the wire are referred to as standing wave or resonant antennas. But, Antennas whose current and voltage distributions are represented by one or more travelling waves, usually in the same direction are referred to as travelling wave or non-resonant antennas. They have uniform distribution of currents and voltages and this can be achieved by proper termination. 7.Def 7.Define ine the radia radiatio tion n resis resistan tance ce of an antenn antenna? a? What What is the import importanc ancee of this this quantity?

It is the radiated power being dissipated in fictious resistance. It is defined as the ratio of power radiated by the antenna o the square of the current at the feed point. 8.What is the power gain of an antenna?

The power gain is the ratio of radiation Intensity in a given direction to the average total input power. 9.What is self-impedance of an antenna?

The impedance at which the transmission line is carrying the RF current from the transmitter to the antenna is known as the self-impedance. 10.Define radiation intensity and directive gain.

Radiation Intensity in a given direction is defined as “ The power radiated from an antenna per unit solid angle”.

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The directive gain is the ratio of Radiation Intensity in a specified direction to the Average radiation intensity. 11.Write short note on effective length of antenna.

The effective length of an antenna is used to indicate the effectiveness of an antenna as a radiator or collector of electro magnetic energy. It is the actual height that is responsible for radiation or reception. 12.What is the relationship between gain and effective area of an antenna?

The gain is directly proportional to the effective area of an antenna. Go = K.D 4π⁄ λ2) Aem Go = α(4π⁄ λ Where α is the effectiveness ratio of an antenna. 13.Define the bandwidth of an antenna.

The band width of antenna is defined as “ The range of frequencies within which the performance of the antenna, with respect to some characteristics [input impedance, beam, width, polarization, side lobe level, gain etc.] Confirms to a specified standard 14.What do you mean by an isotropic radiator?

It is a hypothetical loss less radiator having equal radiation in all directions. E.g. point point source 15.Define the directive gain of an antenna.

The directive gain is the ratio of Radiation Intensity in a specified direction to the Average radiation intensity. 16.State the reciprocity theorem.

If an emf is applied the terminals of an antenna no: 1, and the current is measured at the terminals of another antenna no: 2, then an equal current both in amplitude and phase can be obtained at the terminals of antenna no: 1. If the same emf is applied to the terminals of antenna no: 2. 17. Define the antenna efficiency. efficiency.

Antenna efficiency is defined as the ratio of power radiated to the total input power supplied by to the antenna and is denoted by η. η =

power radiated

=

I 2 Rr

Total power sup plied I 2 [ Rr + Rl ]

Rr = Radiation resis tan ce Rl = loss resis tan ce 18. What is meant by polarization?

It refers time varying behaviours of the electric field strength vector at some fixed point and it also refers the direction of the electric vector in relation to the direction of propagation. 19. Define Define beam width width..

It is defined as the angular width (in degrees) of the major lobe between two directions at which the radiated power in one half of the maximum power. 20.Distinguish between monopoles and dipoles.

Monopole antenna is the vertical antenna of height H = L/2 fed against an infinitely large perfectly conducting conducting plane has the same radiation radiation characteristics characteristics above the plane as does the dipole antenna of length ‘L’ in free space. A dipole antenna is a straight radiator, usually fed in the centre and producing a maximum of radiation in the plane normal to the axis.


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21. What are Maxwell's Maxwell's equations?

The Maxwell’s equations are used for the prediction of the existence of electromagnetic waves and are based on the fundamental laws of (i) Faraday’s law (ii) Amperes circuital law (iii) Gauss law (iv) Displacement current law.

22. Define Define power power gain.

The power gain is the ratio of radiation Intensity in a given direction to the average total input power. 23. What do you unde understa rstand nd by static, static, induction induction and radiation radiation field produced produced by an antenna?

The field terms which vary inversely inversely as the cube of the distance distance [ α 1/r3] are known as electrostatic fields. They are important only near the current elements and does not contribute anything for radiation. Induction field: The field term that varies inversely as the square of the distance [ α 1/r 2] is known as induction field. It predominates at points close to current element where distance is small. Radiation field: The field term that varies inversely as distance “r” is called as radiation fields or “far fields” that accounts accounts for the radiation of electromagne electromagnetic tic waves from the current element. 24. Define Define beam solid solid angle.

The beam solid angle is defined defined as the solid angle through through which all the power of the antenna would flow if its radiation intensity were constant for all angles within the solid angle. 25. Distinguish between resonant antenna and travelling wave antenna.

Linear antennas that exhibit current and voltage standing wave patterns formed by reflections from the open end of the wire are referred to as standing wave or resonant antennas. But, Antennas whose current and voltage distributions are represented by one or more travelling waves, usually in the same direction are referred to as travelling wave or non- resonant antennas. antennas. They have uniform uniform distributi distribution on of currents currents and voltages and this can be achieved by proper termination. 26. What is induction and radiation field of a radiating field?

Induction field: The field term that varies inversely as the square of the distance [ α 1/r 2] is known as induction field. It predominates at points close to current element where distance is small. Radiation field: The field term that varies inversely as distance “r” is called as radiation fields or “far fields” that accounts for the radiation of electromagnetic waves from the current element. 27. What is radiation resistance of antenna? What is its value for half wave dipole and quarter wave monopole?

It is the radiated power being dissipated in fictious resistance. It is defined as the ratio of power radiated by the antenna to the square of the current at the feed point. The value for half wave dipole is 73Ω and for quarter wave monopole is 36.54Ω. 28. Differentiate directive gain and power gain.

The power gain is the ratio of radiation Intensity in a given direction to the average total input power. But the directive gain is the ratio of Radiation Intensity in a specified direction to the Average radiation intensity. 29.Define a short dipole.

A dipole antenna is a straight radiator, usually fed in the centre and producing a


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maximum of radiation in the plane normal to the axis. 30. Sketch the different antenna field zones.

R D

⇒ 0.62 √D3 / λ
R < 0.62 [ √D 3 / λ ]

FresenelDRegion Region

Reactive near field field

R> 2D2 / λ Fraunhofer region

31. Write down the expression for the retarded vector and scalar potentials of current element with sinusoidal variation. 60π I dl sin θ cos ω (t E rad

=

r ) c

λ r

I dl sin θ cos ω (t H rad

−

=

−

r ) c

2 λ r

32.What is Fresnel and Fraunhofer region of radiation?

Fresnel region is defined as the region of the field of an antenna between reactive near field and the far field region. R

D

D

R ⇒ 0.62 √D / λ 2D / λ Fresnel region Fraunhofer pattern Fraunhofer region is defined as that region of the field of an antenna where the angular field distribution is essentially independent of the distance from the antenna. 3

2

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PART-B (16 Marks)

1. Derive the the expressio expressions ns for the the fields radiate radiatedd by an alternatin alternatingg current current element. element. 2. (a) Obtain Obtain general express expressions ions for for the electric electric and magnetic magnetic fields of of oscillating oscillating electric electric dipoles. (b) Explain self impedance and mutual impedance of an antenna. 3. Show the directivi directivity ty of an an alternating alternating current current element element is 1.76dB 1.76dB.. 4. Derive the expression expression for the radiated radiated field field from hertzian hertzian dipole. dipole. 5. Obtain Obtain the expres expressio sionn for the field field produce producedd by an alternat alternating ing curren currentt element element and hence calculate the radiation resistance. 6. (I) Completely Completely specify specify the normali normalized zed radiation radiation pattern pattern with respect respect to field field intensity intensity and polarization of an antenna. (ii) Write a short note on half power beam width.


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7. i. calculat calculatee the radiat radiation ion efficien efficiency cy of an antenn antennaa if the input input power power is 100W and the the power dissipated in it is 1W. ii. Discuss on linear, elliptical and circular polarization polarization of antenna. 8. Explai Explainn the followin followingg antenna antenna characte characteris ristics tics:: i. Bandwidth ii. Antenna temperature iii. Effective ap aperture 9. Explai Explainn the followin followingg antenna antenna characte characteris ristics tics:: i. Radiation resistance ii. Directivity iii. Effective le length 10. Write notes notes on the following: following: i. Isotropic antenna ii. Antenna radiation pattern iii.Half power beam width iv.Front to back ratio UNIT-II WIRE ANTENNAS AND ANTENNA ARRAYS PART-A (2 Marks) 1. Why are arrays used?

Antenna array is an arrangement of several individual antennas so spaced and phased that their individual electric field contributions combine in one preferred direction and cancel in all other directions to get greater directivity. 2. What is a uniform linear array?

A linear antenna array in which the elements are fed with current of equal magnitude and uniform progressive phase shift along the line is called uniform linear array. 3. Differentiate between resonant and non-resonant antenna.

Linear antennas that exhibit current and voltage standing wave patterns formed by reflections from the open end of the wire are referred to as standing wave or resonant antennas. But, Antennas whose current and voltage distributions are represented by one or more travelling waves, usually in the same direction are referred to as travelling wave or non- resonant antennas. antennas. They have uniform uniform distributi distribution on of currents currents and voltages and this can be achieved by proper termination. 4.What is Beverage antenna? Sketch its directional pattern.

This is a non-resonant antenna – in which there is no standing wave- suitable for reception of long wave signals. It is based on the principle of tilting of wave front of the direct ray due to absorption of energy by the surface over which the wave passes. 5.What is the effect of earth on the radiation of antennas?

Effects of earth modifies following (i). Currents flowing in reflecting surface. (ii). Radiation pattern

6.What is null beam width and 3dB beam width?

Null beam width is the angular width of major lobe between two directions at which the radiation becomes zero and the 3dB beam width is the angular width of major lobe between two directions at which the radiated power is one half of the maximum power. 7.Distinguish between standing wave antennas travelling wave antennas.

Linear antennas that exhibit current and voltage standing wave patterns formed by reflections from the open end of the wire are referred to as standing wave or resonant


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antennas. But, Antennas whose current and voltage distributions are represented by one or more travelling waves, usually in the same direction are referred to as travelling wave or non- resonant antennas. They have uniform distribution of currents and voltages and this can be achieved by proper termination. 8.Explain pattern multiplication .

It is stated that as “ The total field pattern of an array of non isotropic but similar sources is the multiplication of the unit radiation pattern and group radiation pattern”. 9. Distinguish between null beam width and half power beam width?

Null beam width is the angular width of major lobe between two directions at which the radiation becomes zero and the 3dB beam width is the angular width of major lobe between two directions at which the radiated power is one half of the maximum power. 10.Mention the types of antenna arrays . There are four types of antenna arrays: (i) Broad side array (ii) End fire array (iii) Collinear array (iv) Parasitic array. 11. Define array factor

The factor by which the antenna array increases the field strength over that of a single element radiating the same total power is called array factor. 12.what is a broad side array?

The simplest array consists of a number of dipoles of equal size, equally spaced along a straight line with the dipole fed in the same phase from the same source. Such an arrangement is called broad side array. 13. For three element binomial array give the values of currents through elements and the radiation pattern.

n = 3; 1:2:3 = 1:2:1 1,2,3 are elements and 1,2,1 are corresponding values of currents 1

1 :

2

2 :

3

1

14. What is end fire array?

In the end fire array each element is fed with same magnitude but different phase and this phases progressive from left to right. 15. Why binomial array is advantageous?

The secondary lobes can be eliminated entirely, if the following two conditions are satisfied (i) Spacing between two consecutive radiating sources does not exceed λ/2 and (ii) The current amplitudes of radiating sources are proportional to the coefficients of the successive terms of the binomial series. 16.What is Dolph-chebychev array?

It is an array designed to make a compromise between binomial array and linear array. It provides a narrowest beam width for a given side lobe level and vice versa. 17.What is the principle of super directive arrays?

An array whose directivity is larger than the directivity of same size is super directivity array. Inserting more number of elements within a fixed length can form this array. 18. Write short notes about Binomial array.


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It is an array in which the current amplitudes of radiating sources are proportional to the coefficients of the successive terms of the binomial series. 19. Give some applications of loop antennas.

i). They are seldom employed for transmission in radio communication, it is mostly used as a receiving antenna, where antenna efficiency is not important. ii). They are also used in radio direction finding (RDF) applications. 20.What is loop antenna?

The loop antenna is radiating coil of any convenient cross section of one or more turns carrying radio frequency currents. It may assume any shape like rectangular, square, triangular, hexagonal and circular loop. Most popular out of this being square and circle. 21.What is Night effect in loop antenna?

A loop antenna will give correct bearings only when no horizontally polarized down coming waves are present. The reason for this is that such waves induce voltages in the horizontal members of the loop that do not cancel out when the plane of the loop is perpendicular to the bearing angle of the radio wave. The result is then either false bearing or an indistinct minimum or both. This action is termed as right effect because the effect of the horizontally polarized waves reflected by the ionosphere is much greater at night than during the day. 22.Mention the antennas used in medium frequency range.

Loop antennas and Tower antenna.

23.What is mean by capacitance hat?

The capacitance hats are installed at the top of the vertical radiator to increase the electrical length of how frequency antenna. It also helps in improving radiation resistance and hence the antenna efficiency. 24.Explain the principle of a tower radiator.

It is a vertical radiator operating with an optimum height from the earth. It si used to provide maximum ground wave radiation i.e radiation in the horizontal direction for the standard broadcast band from 535khz to 1605khz, it is customary to employ a grounded vertical tower or tower radiator. 25.What is the principle of Adcock antenna?

Replacing the loop antenna with an Adcock antenna can eliminate the night error. The circuit is designed in such a way that the horizontally polarized waves do not affect the Adcock antenna. In this antenna the voltage induced in the two horizontal parts due to horizontally polarized down coming sky waves are of same magnitude and phase and hence cancelled out. PART-B (16 Marks)

1. Derive an expression for the bandwidth between first nulls for a broadside array of n elements. 2. (a) Derive the expression for the field produced by uniform linear array and obtain the expression for the beam width of broadside array. (b) What is multiplication of pattern? Give examples for its use. 3. (a) Derive an expression for the beam width of end fire array. (b) How can be the secondary lobes reduced in size in binomial arrays? 4. (a) Obtain the array factor of a binomial array for 6 isotropic radiators. (b) Discuss the effect of earth on radiation pattern of antennas.


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5. Obtain the expression for field and radiation pattern produced by a two element array of isotropic radiators with distance of separation λ and currents of equal magnitude with phase shift of 180 0. 6. (a) Explain the concept of binomial array. (b) Explain the methods of excitation of antennas. 7. Derive the expressions for the fields at a far point due to a small loop antenna. Explain an application of loop antenna. 8. Determine the radiation resistance and directivity of half wave dipole. 9. Discuss on the radiation pattern, radiation resistance and directivity of monopole. 10. Derive the expressions for field components and hence for radiation resistance of half wave dipole antenna. 11.From the first principle derive the expressions of electric field and magnetic field of a short dipole. UNIT- III APERTURE ANTENNAS PART A (2 marks) 1.State Babinets theorem.

In optical physics, Babinets princple states that if the field at any point behind the plane having a screen is added to the field at the same point when complimentary screen is substituted would equal the field at the point when no screen is present. 2.What is slot radiator? What is its operating principle?

When a slot in a large metallic plane is coupled to an R.F source, it behaves like a diploe antenna mounted over a reflecting surface. The slot is coupled to a feed line in such a manner that E-field lies along the short axis of the slot . 3.What is a Cassegrain feed for parabolic reflectors?

In this fed system primary radiator [Horn A] is put at the opening of vertex of parabolode reflector ‘B’. The secondary feed of the cassegrain system is hyperboloid reflector ‘H’ whose focus F coincides with focus of the parabola reflector ‘B’ . 4.Mention some microwave antenna.

i). Parabolic reflector ii). Lens antenna iii). Horn antenna

5.Distinguish between sectorial horn and pyramidal horn.

A rectangular wave guide flared out in only one plane makes a sartorial horn. It flares out width wise so that width ‘w’ of the mouth in larger than the width of the wave guide. The rectangular wave guide flared out in both planes forms a pyramidal horn. Since it flares out in both directions, the width w’ > w and as well as h’ >h. 6.Mention the different types of lens antenna.

Dielectric lens antenna, Metallic lens antenna, Zoned lens antenna, Stepped lens antenna.

7. State uniqueness theorem

Uniqueness theorem states that , for a given set of sources and boundary conditions in a lossy medium , the solution to Maxwell’s equations is unique. 8. What is the main advantage of Cassegrain reflector configuration?

• The main advantage is that the primary feed horn and the associated receiver or transmitter can be located conveniently behind the main reflector. • The necessity of running long transmission lines or waveguides is also eliminated. • Since the horn feed is kept behind the main reflector , one can afford to have a much larger aperture for the horn.


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9.What is the main dis advantage of Cassegrain reflector configuration?

The main dis advantage of Cassegrain reflector configuration is the large aperture blockage by the sub-reflector . Hence, Cassegrain reflector configuration is used only for very large aperture antennas having gain greater than 40dB. 10. What are the drawbacks of lens antenna?

• Due to the reflection at the dielectric-air interface, a matching quarter wave transformer is required which limits the band width of the lens antenna to the bandwidth of the matching device. • A lens antenna is generally heavy and bulky. 11. What is ‘zoning’ in lens antenna? Zoning is a method used to reduce

the bulk of the antenna. The lens is divided in to several circular zones and the dielectric material is removed from each zone such that the electrical path length between adjacent zones differs by an integer multiple of a wave length. 12. What are the two methods of ‘zoning’ in dielectric lens antenna?

zoning the non-refracting surface , zoning the refracting surface

13. State Snell’s law of refraction. sin θ t sin θ i θ i

=

=

∈r 1 ∈r 2

angle of incidence, θ t

=

angle of refraction

∈r 1 =

relative dielectric cons tan t of region1

∈r 2 =

relative dielectric cons tan t of region2

14. Give the applications of lens antenna.

They are used in the higher end of the microwave spectrum and millimetre wave frequencies. 15. Mention any three aperture antennas.

Horn antenna, slot radiator,Lens antenna

16. What is the dual parameter of J and E? Dual parameter of J is M, Dual parameter of E is H 17. What is a pyramidal horn?

The rectangular wave guide flared out in both planes forms a pyramidal horn. Since it flares out in both directions, the width w’ > w and as well as h’ >h. 18. What is a sectoral horn?

A rectangular wave guide flared out in only one plane makes a sartorial horn. It flares out width wise so that width ‘w’ of the mouth in larger than the width of the wave guide. 19. What is a corner reflector?

A corner reflector is made up of two flat-plate reflectors joined together to form a corner. The corner reflector is generally used in conjunction with a dipole or dipole array kept parallel to the corner line. Corner reflector gives a higher directivity. 20. Mention any three curved reflector shapes?

Parabolic, Parabolic cylinder, Hyperboloid

PART-B (16 marks)

1. i. State and explain uniqueness theorem. ii. Give an account on aperture antennas.


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2. Explain the following principles: i. Field equivalence principle ii. Duality principle 3. Explain the Cassegrain reflector configuration and mention its advantages and disadvantages. 4. Explain the construction and special features of various types of Horn antenna. 5. Explain the following antenna i. Slot radiator. ii. Parabolic dish. 6.Explain the construction and special features of lens antenna. 7. Explain the construction and special features of sectoral Horn antenna. 8. Explain the construction details and application of any two aperture antenna. 9. Discuss on the feeding mechanisms of parabolic dish antenna. 10. Write notes on the following: i. Pyramidal Horn antenna ii. Zoned lens antenna

UNIT IV SPECIAL ANTENNAS AND ANTENNA MEASUREMENTS PART A (2 marks) 1.Give some applications of rhombic antenna.

The applications of Rhombic antennas are i). HF transmission ii). HF reception

2.What is the reason for using Yagi antenna in TV broadcast reception?

Yagi antenna is essentially a fixed frequency device i.e frequency sensitive and a bandwidth of about 3% is obtainable. This much bandwidth is sufficient for TV reception. 3.What is Wide Band antenna? Give example.

Antennas which maintain certain required characteristics like gain, front to back ratio, SWR, Polarization input impedance and radiation pattern over wide range of frequencies are called wide band or broad antennas. Log periodic antenna is a broadband antenna. 4.What are parasitic elements and where are they used?

Reflector and director are passive elements which are not connected to the feeder line directly, but they are simply grounded and are called parasitic elements. The parasitic elements receive their excitation from the nearby driven element. They are used in Yagi uda array for TV reception. 5.What is log periodic antenna?

Log periodic antenna is a broadband antenna, it has number of dipoles of different lengths. The performance of the system is periodic as the logarithmic function of frequency that results the name. 6.What is folded dipole antenna? What is its input impedance?

Folded dipole has got a versatile quality of providing any desired input impedance by increasing the number of elements and selecting lengths of dipole. Its input impedance is 292 Ω. 7.Explain the concepts of parasitic elements.

Reflector and director are passive elements which are not connected to feeder line directly and are called parasitic elements. The parasitic elements receive heir excitation from the voltages induced in them by the current flow in the driven element. The phase and currents flowing due to the induced voltage depend on spacing between the elements and upon the reactance of the elements.


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8.Differentiate between director and reflector.

The length of the reflector is greater than the length of the Active or driven element and both are placed very close to each other. But the length of the Director is smaller than the length of the driven element and is placed apart from each other. 9.What is the principle of V antenna?

Two long wires are arranged in the form of ‘V’, since two wires are super imposed, the fields along the axis of the antenna become doubled while the field normal to the axis are neutralized. So the resultant field pattern is bi-directional. The two ends may be terminated by connecting a 500Ω resistor between each end to ground in order to get the unidirectional pattern. 10.What is Helix antenna?

Helical antenna is broadband VHF and UHF antenna to provide circular polarization characteristics. It is used in extra terrestrial communication in which satellite relays etc. are used. 11.What are the diff types of antenna used in at very high frequency?

Yagi uda antenna, Log periodic antenna and Slot antenna.

12. Describe the slotted line technique for impedance measurement.

This method is used for measuring the unknown input impedance at high temperatures. It makes use of voltage or current standing wave ratio (VSWR) i.e. the ratio between two voltage or current minima and the reference point at which impedance is going to be measured. 13.How the radiation resistance of a given antenna can be measured.

The radiation resistance of a given antenna can be measured using reflection coefficient method. 14.Write short notes on measurement of antenna pattern.

• For pattern measurement , the antenna is used in the receive mode. The antenna is kept at a distance

R

>

2 D λ

2

transmitting electromagnetic energy

, so that it produces a plane wave at the location of the receive antenna. • The receive antenna is rotated , keeping the position of the transmit antenna unaltered. • The field pattern, phase pattern, polarization pattern, etc, are measured using the same arrangement but with different sensors to measure the corresponding parameters instead of the received power. 15. What is the condition required when gain of an antenna is measured by comparison method ?

It is important that the secondary antenna and associated transmitter should be stable irrespective of frequency. There should not be any variation in the frequency of radiated power in the direction of primary antenna throughout the measurement. 16. What is the input impedance of folded dipole antenna?

Input impedance of folded dipole antenna is 292 ohms

17. Give the typical dimensions of 3 element Yagi-Uda antenna.


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Length of the driven element : 0.47 λ Length of the director element : 0.442 λ Length of the reflector element : 0.482 λ

18. What is the effect of number of directors on the directivity of Yagi-Uda antenna?

As the number of directors increases, the directivity also increases.

19. Give the application of Turnstile antenna.

Turnstile antenna is used for transmitting Television signals.

20.What is the antenna used for mobile and wireless hand set applications?Give reason.

Helical antenna operating in the normal mode is used for mobile and wireless hand set applications. A normal mode helical antenna is compact and has an omni directional radiation pattern in the plane normal to the axis of the helix. PART-B (16 marks)

1. With suitable diagrams explain how gain and half power beam width of an antenna can be measured. 2. i. Explain a method of determining the impedance of antenna. ii. How radiation pattern and hence beam width of antenna is determined? 3 i. Describe the voltage standing ratio method of measuring antenna impedance. ii.Reflection coefficient of an antenna is measured to be 0.12∠120 . If the characteristic impedance of the measurement system is 50 Ω, calculate the antenna impedance. 4. Explain the typical construction of an anechoic chamber. 5. Explain the construction, radiation pattern and features of the rhombic antenna. 6. Justify how the log-periodic antenna can be used as a wide band antenna, by explaining its method of operation. 7 .i. Explain the construction and features of micro strip antennas. ii. Design a rectangular micro strip antenna with dielectric constant of substrate as 2.2, h=0.1588 cm so as to resonate at a frequency of 10 GHz. 8. Explain the working of biconical antenna and derive the expression for input impedance. 9. Explain the construction, radiation pattern and features of helical antenna. 10. i. Describe the construction and working principle of Yagi-Uda antenna. ii. Calculate the dimensions of a Yagi-Uda antenna that has a directivity of 12dB at 145MHz. 11. Explain the construction, radiation pattern and features of turnstile antenna. 12. Write notes on: i. V antenna ii. Spiral antenna 13. Why a large bandwidth and high impedance is required for a TV Rx antenna. Describe an antenna used for this purpose. o

UNIT – V RADIO WAVE PROPAGATION PART A (2 marks) 1.Write down the Sommer field equation.


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Where,

DEPARTMENT OF ECE

Eg = A (Eo / r) Eo is the field strength of ground wave at the surface of the earth at unit

distance from the transmitting antenna neglecting earth losses. is gound field strength is distance between transmitting antenna. is Attenuation factor

Eg r A 2.Why is diversity reception necessary?

Due to the general fading, there is a considerable variation in the strength of short wave signals received by common receivers through ionosphere. The diversity receiving systems provide a high and intelligible level of received signals at all times. 3.What is sun spot cycle?

The sun has a 11 year cycle (sun spot cycle) over which its output varies tremendously. Although the light are slight, but the solar output of ultra-violet rays, coronae, Hares, particles radiation and sun spots may vary fifty fold over that period. 4.Mention the various ionosphere layers.

D layer, E,F1 and F2 layers are various ionospheric layers.

5.What are the different types of fading encountered in the sky wave propagation? What are the ways to overcome this effect?

Selective fading, Interference fading, Absorption fading, Polarization fading and Skip fading are the different types of fading. Using exalted carrier reception can reduce the selective fading. The interference can be minimized either by space diversity or frequency diversity. The best way to minimize fading is diversity reception. 6.What is duct propagation?

The ground surface and atmospheric layer form a duct or sort of “leaky wave guide” which guides the electromagnetic wave between its walls. When frequency is high, the region where the refractive index is usually high, traps the energy and causes it to travel along the earth surface as happens in a wave-guide. This type of propagation is called duct propagation. 7.What is magneto-ionic splitting?

The earth magnetic field splits up the incident radio waves into two components of the ordinary and the extraordinary waves. The two waves have elliptical polarization and rotate in opposite direction. They have different energy absorption and velocities. The phenomenon of splitting of wave into two different components by the earth’s magnetic field is called as magneto-ionic splitting.

8.Define critical frequency.

The highest frequency of wave that will be reflected from a given layer is known as critical frequency of the given layer fc = 9 N max Where N max --- Maximum electron density 9. Explain diversity reception.

The basic principle behind the diversity system is to duplicate some part of the signal or system in the hope that even if one part experiences a deep fade or distortion, the other part may not. 10.What is optimum working frequency?


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The frequency normally used for ionospheric transmission is known as the optimum working frequency. It is chosen to be about 1.5% less than MUF. It is also known as optimum Traffic frequency. 11.Define virtual height.

Virtual height of an Ionospheic layer may be defined as the height to which a short pulse of energy sent vertically upward and travelling with the speed of light would reach taking the same two ways travel time as does the actual pulse reflected from the layer. 12.Give the range of convergence of and frequency range of ground wave, sky wave and space wave propagation modes.

The ground wave propagation takes place up to 2MHz. Sky wave propagation is suitable for short waves of frequency from 2MHz to 30MHz. Space wave communication is used from 30MHz onwards. 13.What do you mean by gyro frequency?

In ionospheric layer the vibration of electron will make a path of very narrow ellipse due to the smaller amplitude of vibration. The tendency continues until the frequency is lowered o appoint at which cyclotron resonance occurs and then the electrons will follow a spiral path of steadily increasing radius along with the velocity also increases. This occurs at 1400 KHz cycle is termed as Gyro frequency. 14.How are critical frequency and max usable frequency related?

The maximum usable frequency and critical frequency can be related by the equation of f MUF = f c √(1+(D/2h)2) Where f MUF = Maximum usable frequency f c = Critical frequency D = propagation distance , h = Height of the ionosphere layer 15.What do you mean by selective fading.

Selective fading produces serious distortion of modulated signals. Since the fading is frequency selective, it is just possible for adjacent portion of a signal to fade independently, although their frequency separation is only a few dozen hertz. 16.What is mean by wave tilt in ground wave propagation?

The ground or surface wave will be attenuated due to ground attenuation i.e. due to diffraction and tilt in the wave front. As the wave progress over the curvature of the earth, the wave front starts gradually tilting more and more. This increase in the tilt of wave causes more short circuit of the electric field component and hence the field strength goes on reducing, ultimately at some appreciable distance from the transmitting antenna, the surface wave dies because of the losses. 17.What are the different ionosphere layers? Give its approximate heights and electron densities.

The different layers of ionospheric region, corresponding height and electron density are given below: LAYER HEIGHT ELECTRON DENSITY 1. D –region 50-90 km 10 14 –1016 /cm3 2. Normal E –region 90-140 km 10 5 – 4.5 x 10 5 during day 5 x 103 – 104 during nighttime 3. Sporadic region 90-130 km Ten times to that of normal E -region 4.F1 layer 140 – 250 km 2 x 10 5 – 4.5 x 10 5 F2 layer 250 – 400 km 3 x 10 5 – 2 x 106 18.What is the effect of earth’s magnetic field in sky wave propagation?


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In Ionosphere, the electrons are set in motion by the electric field of the radio wave and the earth’s magnetic field, and then exert a force on the vibrating electrons producing twisting effect on their paths. This reacts on the incident radio waves. 19.What is scatter propagation?

Forward scatter propagation or simply scatter propagation is of practical importance at VHF, UHF and microwaves. UHF and microwave signals were found to be propagated much beyond the line of sight propagation through the forward scattering in the tropospheric irregularities. It uses certain properties of troposphere and is also known as Troposcatter. 20.What is MUSA system? What is its underlying principle?

MUSA system is employed during diversity reception, which is used to avoid Synchronous or general fading. Although rhombic arrays may be used in all types of diversity reception, but a more elaborate system of diversity reception is known as MUSA system in short wave reception. Since the system consists of many antenna units and the vertical directivity of entire system is steerable i.e. adjustable and hence it is called as Multiple Unit Steerable Antenna. 21.What are the causes for abnormalities in the ionosphere.

i).Sudden ionospheric disturbances ii). Ionospheric storms iii).Sun spot cycle iv).Tides and winds in the Ionosphere v).Fading vi).Whistles vii) Ionospheric Cross-modulation viii).Atmospheric Noise

22.Write short notes about ground wave propagation.

The ground wave propagation is due to ground wave, which is guided along the surface of the earth. The waves must be vertically polarized to prevent short-circuiting of electric component. Since the earth’s attenuation increases with increase of frequency, ground wave propagation is limited up to 2Mhz only. It is suitable daytime local broadcast. 23.How the virtual height can be measured?

• Virtual height can be measured using ionosonde. • Ionosonde is the instrument used to measure the virtual height of the ionosphere. This instrument transmits an RF pulse vertically in to the ionosphere from the ground. This pulse is reflected from the ionosphere and is received by the ionosonde. • The time delay between the transmit and the receive pulse is measured which is a measure of the virtual height of the ionosphere. PART-B (16 marks)

1. i. Explain the important features of ground wave propagation. ii. Explain the concept of super refraction. 2. i. Obtain the expression for the field strength of space wave signal. ii. Describe the need for diversity reception & typical schemes. 3. Establish the following relationship in ionosphere propagation f c = √81 Nmax Where: f c – critical frequency & Nmax – max ionisation density.


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4. i. Explain how ionosphere layers are formed. ii. Obtain an expression for the critical frequency of an ionospheric layer. 5. Bring out the important features of ground wave propagation, sky wave propagation & ionosphere propagation of radio waves mentioning the areas of application. 6. i. Obtain the expression for the range of space wave propagation. ii. Describe the characteristic features of various layers in the ionosphere. 7. Why radio waves passing through ionosphere are attenuated ? State briefly the factors which Influence the degree of attenuation. 8. What does “The Effective Radius” of earth mean? Discuss the effect of changes in Atmosphere on space wave propagation. 9. Explain the following: i.Tropospheric scattering ii. Effect of earth’s magnetic field in the ionosphere 10. i. Derive the expression for refractive index of the Ionosphere(neglecting Earth’s magnetic field effects) ii. Explain the characteristics of different ionized regions of Ionosphere, drawing the structure above the earth. 11. i. Show that the radius of curvature of wave path is function of rate of change of dielectric constant (or) refractive index with height in space wave propagation. ii. Explain ground wave propagation and obtain expression for field strength.


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St.Joseph’s College of Engineering Department of Electronics and Communication Engineering EC 2352: COMPUTER NETWORKS VI SEMESTER

UNIT I: DATA COMMUNICATION 1.Define the term data communication.

Data communication is the exchange of data between two devices through some form of transmission medium. 2.Mention the fundamental characteristics of data communication systems.

(i) Delivery: The system must deliver data to the correct destination. Data must also be received by the intended device or user and only by that device or user. (ii) Accuracy: The system must deliver data accurately. Data that have been altered in transmission and left uncorrected are unusable. (iii) Timeliness: The system must deliver data in a timely manner. Data delivered late are useless. 3.Mention the components of Data communication system . 1.Message , 2.Sender, 3.Medium, 4.Protocol , 5.Receiver. 4.What’s a computer network?

A computer network is a set of devices connected by media links. The links connecting the devices are called as communication channels. Its size, its ownership, physical architecture and the distance it covers determine the type of network. 5.Give the classifications of computer networks.

1.LAN , 2.WAN ,3.MAN

6.List out uses of computer networks.

1. To store & manipulate information, 2.Make decisions & manipulate data. 3.Move information from one system to another. 7.Mention the advantages of having computer networks.

Sharing of resources, Exchange of data within a company, Flexible work environment. 8.What’s meant by line configuration?

It refers to the way two or more communication devices attach to a link. A link is a physical communication pathway that transfers data from one device to another. Two different types of line configurations are: 1.Point-to-point 2.Multipoint 9.What’s meant by Topology of a network?

Topology refers to the way a network is laid out, either physically or logically. The topology of a network is the geometric representation of the relationships of all links and linking devices to each other. There are 5 basic topologies possible: (1) Mesh (2) Star (3) Tree (4) Bus (5) Ring 10.What’s a hub?

In star topology each device has a dedicated point-to-point link only to a central controller called as hub. The hub acts as an exchange (i.e.) if one device wants to send data to another, it sends data to another, it sends the data to the controller, which then relays the data to the other connected device. 11.What’s an active hub?

An active hub contains a repeater, which is a hardware device that regenerates the received bit pattern before sending them out. Repeating strengthens transmissions and increases distance a signal can travel. 12.What’s meant by transmission mode?

It defines the direction of signal flow between two linked devices. There are 3 types of transmission modes: 1.Simplex: Unidirectional communication. 2.Half-duplex: Bi directional, but not simultaneous utilization of link. 3.Full-duplex:

Bi directional, simultaneous utilization of link.


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13.What’s a LAN?

LAN is a data communication network within a building, plant (or) campus (or) between nearby buildings. 14.What’s MAN?

A data communication network system covering an area the size of a town or city. 15.What’s WAN?

A data communication network spanning states, countries or the whole world.

16.What’s protocol?

A set of rules that govern all aspects of information for communication.

17.What’s a standard?

A standard that provides a model for development that makes it possible for a product to work regardless of individual manufacturer. 18.Mention the types of conversion of data.

analog.

1.Digital-to-digital

2.Digital-to-analog

3.Analog-to-digital

4.Analog-to-

19.Distinguish BIT RATE and BAUDRATE.

Bit rate – No.of bits per second.

Baud rate – No.of signal units per second.

20.List mechanisms of modulating digital data into analog signal .

1.Amplitude-shift-keying (ASK).2.Fequency-shift-leying (FSK)

3.Phase-shift-keying (PSK)

21.List analog-analog modulation techniques.

1.Amplitude modulation.2.Frequency modulation.

3.Phase modulation.

22.What’s meant by DTE and DCE?

DTE (Data Terminal Equipment) – source for binary digital data. DCE (Data Circuit terminating equipment) – receives data from a DTE and changes it into a form appropriate for network transmission. Also performs the reverse transformation. 23.Give the necessity for interface standards DTE-DCE interfaces.

They try to define the mechanical, electrical, functional characteristics of the connection between DTE & DCE. 24.What’s a modem?

The most familiar type of DCE is a MODEM. A device, which consists of a modulator & a demodulator. It converts digital signal into an analog signal and vice versa. 25.List the design factors for transmission media.

1.Bandwidth

2.Transmission impairments

3.Interference

4.Numberof receivers.

26. What are the Advantages of distributed processing?

In distributed processing a task is divided among multiple computers. Instead of a single large machine being responsible for all aspects of a process each separate computer handles a subset. Advantages of distributed processing

1. Security/encapsulation 2.Distributed databases 3.Faster problem solving 4. Security through redundancy 5. Collaborative processing

27. Distinguish between a peer-peer relationship and a primary-secondary relationship. • •

Peer-to-peer relationship: The devices share the link equally. Primary-Secondary relationship: One device controls traffic and the others must transmit through

it. 29. What are advantages of a multipoint connection over a point-to-point connection?

• • •

In multipoint connection more than two specific devices share a single link The capacity of the channel is shared spatially or temporally But in point-to-point connection a dedicated link is provided between two machines

30. Which OSI layers are the network support layers?

1. Physical layer 2. Data link layer 3. Network layer 31. What is the difference between network delivery and Transport layer delivery?


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The network layer is responsible for the source-to-destination delivery of a packet. It treats each packet independently, even though they belong to the same message. • Transport layer delivery: The transport layer is responsible for source-to-destination (end-to-end) delivery of the entire message.

•

Network layer delivery:

32. List the layers of the OSI model

1. Physical layer 2.Data link layer 3.Network layer 4.Transport layer 5.Session layer 6.Presentation layer 7.Application layer

33. What are the responsibilities of the session layer? 1. Dialog control: The session layer allows two systems enter into a dialog 2. Synchronization: The session layer allows a process to add checkpoints into a stream of data to

achieve synchronization between sender and receiver.

34. What are the responsibilities of the presentation layer? 1.

The presentation layer is responsible for interoperability between the different encoding methods used in different computers. The presentation layer at the sender changes the information from its sender-dependent format into a common format. The presentation layer at the receiving machine changes the common format into its receiver-dependent format. 2. Encryption/Decryption: To carry sensitive information, a system must be able to assure privacy. Encryption means that the sender transforms the original information to another form and sends the resulting message out over the network. Decryption reverses the original process to transform the message back to its original form. 3. Compression: Data compression reduces the number of bits to be transmitted. Translation:

35. How do the layers of the TCP/IP protocol suite correlate to the layers of the OSI model?

• • •

The TCP/IP protocol suit is made of five layers: Physical, data link, network, transport and application. The first four layers provide physical standards, network interface, internetworking, and transport functions that correspond to the first four layers of the OSI model. The three topmost layers in the OSI model are represented in TCP/IP by a single layer called the application layer.

36. How does NRZ-L differ from NRZ-I?

S.No

1 2 3

NRZ-L

NRZ-I

Nonreturn to zero, level encoding Nonreturn to zero, invert encoding A positive voltage represent bit 0 & An inversion of the voltage level represent bit 1 A negative voltage represent bit 1 A bit 0 is represented by no change (or vice versa) Synchronization i s not p rovided f or a long NRZ-I is superior to NRZ-L due to the stream of 0s or 1s in the data synchronization provided by the signal change each time a bit 1 is encountered.

4

Example 0 1 0 0

0 1 0 0

1 1 1

1 1 1 0

Time

37. What is the purpose of a null modem?

• Null modem is used to connect two compatible DTEs (Computers) in the same building. • It provides the DTE-DTE interface without the DCEs. (modems) • A null modem is an EIA-232 interface that completes the necessary circuits to fool the DTEs at either end into believing that they have DCEs and a network between them.


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38. Mention the disadvantages of OSI model.

1. Bad timing 2. Bad technology 3. Bad implementation 4. Bad politics PART B

1.What is the use of Layered Architecture? Describe Briefly the OSI Layers that are the responsible for the following i)Determining the best path to route packets (6) ii) Providing End- to –End communication with reliable service (6) iii) Providing node to node communication with reliable service (4) 2. Describe Briefly the ISO-OSI Layers in detail (16) 3. Explain briefly the different types of Guided and Unguided transmission media used for data communication (16) 4. Explain the different types of Topologies in detail (16) 5. What does the term Modem stand for? Explain different types Modems. (16) 6. Write short notes on Analog to analog Encoding method (16) 7. Explain briefly the Digital to analog Encoding method (16) 8. With suitable example explain Digital to digital Encoding method (16) 9. Describe the data pins of Null modem (16) 10.Explain the RS232 Interface in detail. (16)

UNIT-II: DATA LINK CONTROL AND PROTOCOLS 1.What are the three main functions of the data link layer? • Line discipline: It coordinates the link system; it determines which device can send and when it can

send.

• •

Flow control: It coordinates the amount of data that can be sent before receiving acknowledgement. Error control : It allows the receiver to inform the sender of any lost or damaged frames and

coordinates the transmission of those frames by the sender. 2.What is the mechanism of stop and wait flow control?

In stop and wait method of flow control, the sender waits for an acknowledgement after every frame it sends. Only when an acknowledgement has been received the next frame is sent. 3.What is the mechanism of sliding window flow control?

In the sliding window method of flow control the sender can transmit several frames before needing an acknowledgement. The receiver uses a single acknowledgement to confirm the receipt of multiple data frames. 4. List out the different types Flow Control Schemes

a) Stop and Wait Flow Control

b) Sliding Window Flow Control

5.An ACK 3 in sliding window flow control (window size of 7) means that frame three is next operated by the receiver. 6.ARQ stands for automatic repeat request. 7.Why are asynchronous protocols losing popularity?

The asynchronous protocols have inherent slowness hence they are replaced by higher speed synchronous mechanism. 8.What is piggybacking?

Piggybacking means combining data to be sent and acknowledgement of the frame received in one single frame. 9.How are synchronous protocols classified? What is the basis of the classification?

Synchronous protocols can be classified into two groups depending upon the interpretation of frames

as

• •

Character-oriented protocols: interprets a transmission frame as a succession of characters Bit-oriented protocols: interprets a transmission frame as a succession of individual Bits.


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10.Name and discuss briefly the bits in the HDLC control field.

I-frame 0 S-frame 1 0 U-frame 1 1 • P/F • N(s) • N(r) • Code

-

P/F

N(r)

P/F

N(r )

P/F poll / final bit has meaning only when set to 1. sequence number of frame sent. sequence number of next frame expected. code for supervisory or unnumbered frame.

code

11.How do character –oriented protocols convey control information?

In character oriented protocol the control information is conveyed in the form of an existing character encoding system, eg. ASCII characters. 12.HDLC is an acronym for High Level Data Link Control. 13.BSC is a character-oriented protocol. 14.How are data-link protocols divided into classes? What is the basis of the division?

Data-link protocols are classified into two groups depending on the type of transmission as 1.Asynchronous protocols 2. Synchronous protocols 15.Name the five categories of U-frames.

The five categories of U-frames are Mode setting, Unnumbered exchange, Disconnection, Initialization mode, Miscellaneous 16.Name the four types of S-frames.

Receive ready, Receive not ready, Reject, Selective reject 17.The shortest frame in the HDLC protocol is usually the management frame. 18.What are the two main methods for error control?

1. Stop and wait 2. Sliding window 19.What is the use of p/f bit in the HDLC frame?

The poll/final bit has meaning only when set. The bit is called poll bit when data is transmitted from primary station to secondary station and is called final bit when data is transmitted from secondary station to primary station.

20. In what way sliding window flow control is more efficient than stop and wait flow control? • • • •

The disadvantage of stop and wait flow control is inefficiency and slow. In situations where the bit length of the link is greater than the frame length, the facility of the link is not utilized efficiently in stop and wait flow control. Efficiency can be greatly improved by allowing multiple frames to be in transit at the same time. This method is implemented in sliding window flow control. To keep track of which frames have been acknowledged, each is labeled with a sequence number.

21. Define data transparency.

Data transparency in data communication is the ability to send any combination of bits as data.

22.What is Bit stuffing? Apply Bit Stuffing for the given data: 011011111111111111110010

• •

Bit stuffing is the process of adding one extra 0 whenever there are five consecutive 1s in the data so that the receiver does not mistake the data for a flag. The bit stuffed data is 011011111011111011111010010

23. Give examples for asynchronous data link protocols

1. XMODEM 2. YMODEM 3. ZMODEM 4. BLAST 5. KERMIT

24. Draw the HDLC frame format.

Flag Control Address Data FCS Flag Flag value: 01111110 FCS: Frame Control Sequence 25. What are the advantages of FDDI over a basic Token Ring? S.No FDDI


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EC2353 ANTENNA AND WAVE PROPAGATION 1 2

3 4

Data rate: 100Mbps Access method: Timed Token passing. In this method each station may send as many frames as it can within its allotted access period. Transmission of Real time information ( S-frame ) is possible  FDDI is implemented as a dual ring. Data is transmitted along the primary ring.  The secondary ring makes FDDI self-healing  Whenever a problem occurs on the primary ring, the secondary can be activated to complete data circuits and maintain service.

DEPARTMENT OF ECE

4 & 16Mbps only Access method is Token passing: In this method, each station is permitted to send only one frame in its turn. Not possible 



In Token ring, one disabled or disconnected node could stop the flow of traffic around the entire network. To solve this problem each station is connected to an automatic switch that require extra hardware.

26. Why is there no AC field in the 802.3 frame? 



Access control (AC) field in token ring frame specify the priority level to each station, so that each station sends data during its turn. But CSMA/CD access method does not specify priority level for any station. So there is no AC field in the 802.3 frame.

27. What types of transmission media are used in LANs? 

 

Types of LANs 1. Wired LAN 2. Wireless LAN Transmission media in Wireless LAN is radio wave Transmission media in Wired LAN are 1. Coaxial cable 2. Unshielded Twisted Pair cable (UTP) 3. Shielded Twisted Pair cable (STP) 4. Fiber optic cable

28. What is the difference between base band and broadband?

S.No 1 2

Base band The word base specifies a digital signal

Broadband The word broad specifies an analog signal. The different standards are 10Base-5, 10Base-2, The only one specification for 10BaseT, 100Base-T, 1Base-5 broadband is 10 Broad-36 Where the first number indicates the data rate and the lost number defines the maximum cable length.

29. The PDU is a product of the LLC sublayer

a) 802.3 frame b) 802.5 frame c) PDU d) Preamble 30. FDDI is an Acronym for Fiber Distributed Data Interface. 31. Suppose there is heavy traffic on both a CSMA/CD LAN and a Token Ring LAN. A station on which system is more likely to wait longer to send a frame? Why? 



A station on a CSMA/CD LAN is more likely to wait longer to send a frame than a Token ring LAN. Because there is no way to predict either the occurrence of collisions or the delays produced by multiple stations attempting to capture the link at the same time in CSMA/CD LANs. But in Token ring, each station may transmit only during its turn and may send only one frame during each turn.

32. Why are services such as DQDB and SMDS used in MANs?  



A Metropolitan area network(MAN) is a network designed to extend over an entire city. When LANs of a single enterprise are distributed over a larger area, however, privately owned connecting infrastructure is impractical. Most organizations find that even if they could get permits to lay cable on public land, a better alternative is to use the services of existing utilities.


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So, services such as DQDB and SMDS are used in MANs.

33. How are slots generated in DQDB? 



Head stations in the dual bus configuration of DQDB generate the empty slots in which transmitting station drops data into it and the intended destination station reads the data. . The slot is the 53-bytes information, which consists of 48 bytes payload and 5 bytes header.

34. Why was the slot size chosen to be 53 bytes in DQDB? 

To make compatible with the size of a cell in Asynchronous Transfer Mode (ATM), the slot size in DQDB was chosen to be 53 bytes.

35. What is the use of HUB?   

A HUB is a central controller in a star topology. Each device has a dedicated point-to-point link only to the hub. When a station sends a frame to a hub, the frame is sent out from all ports and every station will receive it.

36. What is CSMA/CD?   





CSMA/CD is the access method used in an Ethernet. It stands for Carrier Sense Multiple Access with Collision Detection. Collision: Whenever multiple users have unregulated access to a single line, there is a danger of signals overlapping and destroying each other. Such overlaps, which turn the signals into unusable noise, are called collisions. In CSMA/CD the station wishing to transmit first listens to make certain the link is free, then transmits its data, then listens again. During the data transmission, the station checks the line for the extremely high voltages that indicate a collision. If a collision is detected, the station quits the current transmission and waits a predetermined amount of time for the line to clear, then sends its data again.

37. What is FDDI and its use?   



FDDI is a LAN Protocol standardized by ANSI & ITU-T. It stands for Fiber Distributed Data Interface. It supports data rate of 100 Mbps and provides a high-speed alternative to Ethernet and Token Ring. It specifies timed token passing access method and dual ring configuration.

38. What does IEEE 10 Base 5 standard signify?  



It is Ethernet standard. The number 10 signifies the data rate of 10 Mbps and the number 5 signifies the maximum cable length of 500 meters. The word Base specifies a digital signal with Manchester ecoding.

39. What is token ring?    

 

Token ring is a LAN protocol standardized by IEEE and numbered as IEEE 802.4. In a token ring network, the nodes are connected into a ring by point-to-point links. It supports data rate of 4 & 16 Mbps. Each station in the network transmits during its turn and sends only one frame during each turn. The mechanism that coordinates this rotation is called Token passing. A token is a simple placeholder frame that is passed from station to station around the ring. A station may send data only when it has possession of the token.

40.Differentiate 1000base SX and 100 Base FX. S.No Feature

1 2 3 4 5 6

Type Data rate Medium Signal Max. Distance Encoding

1000 Base SX

Gigabit Ethernet 1 Gbps Optical fiber Short-wave laser 550m 4B/5B

41.Name and explain the functions of the timers used in FDDI  Token Rotation Timer (TRT): The TRT runs

100 Base FX.

Fast Ethernet I00 Mbps. Optical fiber Laser 2000m 8B/10B continuously and measures the actual time

taken by the token to complete a cycle.


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The THT begins running as soon as the token is received. Its function is to show how much time remains for sending asynchronous frames once the synchronous frames have been sent. Token Holding Timer (THT):

42. What is daisy chaining in Ethernet? 





StarLAN allows as many as 10 stations to be linked, each to the next, in a chain in which only the leading device connects to the hub. This mechanism is called daisy chaining in which the range of the StarLAN can be increased. The StarLAN is 1 Base 5 Ethernet.

43. What is the need for MAC sublayer in LANs? 

 



Project 802 has split the data link layer into two different sublayers 3. Logical Link Control (LLC) 4. Medium Access Control (MAC). MAC sublayer resolves the contention for the shared media. It contains the synchronization, flag, flow and error control specifications necessary to move information from one place to another, as well as the physical address of the next station to receive and route a packet. It is the lower sublayer of the data link layer.

44. Differentiate Collision and Congestion. Collision: Whenever multiple 







users have unregulated access to a single line, there is a danger of signals overlapping and destroying each other. Such overlaps, which turn the signals into unusable noise, are called collisions. Congestion: Congestion in a network may occur if users send data into the network at a rate greater than that allowed by network resources. Congestion may occur because the switches in a network have a limited buffer size to store arrived packets before processing. Congestion in a network is a problem that must be avoided because it decreases throughput and increases delay. PART B

1. With neat diagram explain the various Flow Control Mechanisms available in Data link layer (16) 2. With neat diagram explain the various Error Control schemes available in Data link layer (16) 3. Briefley explain Station types, Configurations, Modes of Communications and Frame Format of HDLC. 4. With neat diagram explain the access method, Electrical specification, Implementation and Frame format of IEEE 802.3 Standard in detail. 5. With neat diagram explain the access method, Electrical specification, Implementation and Frame format of IEEE 802.4 Standard in detail. 6. With neat diagram explain the access method, Electrical specification, Implementation and Frame format of IEEE 802.5 Standard in detail. 7. Explain the various features of Wireless LAN Standard. 8. With suitable example, explain the working principle of Cyclic Redundancy Check 9. With suitable example, explain any one Error Detecting and Correcting Scheme. 10.What is SONET? Explain the SONET Devices, Layers, and Types of Headers with neat diagram. Unit – III NETWORK LAYER 1. Define address space.

Total number of address used by the protocol. 2.what is the address space of IPv4?

232= 4,294,967,296

3.change the following IPv4 address from binary notation to dotted decimal notation. 10000001 00001011 00001011 11101111

129.11.11.239 4.What is netid and hostid used in classful addressing?

Portion of the IP address that identifies the network is called netid and portion of the IP address that identifies the host or router is called hostid 5.What are the restrictions in classless addressing?


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The number of addresses needs to be a power of 2; the mask needs to be included in the address to define the block; starting address must be divisible by the number of address in the block. 6.How many types of addresses available in IPv6?

Unicast, multicast and anycast 7.What is the address space of IPv6?

2128

8. What is address mapping?

Mapping a logical address to physical address or vice versa. 9.What is static mapping?

Involves the creation of a table that associates a logical address with a physical address.

10.What are the limitations in the static mapping?

A machine can change its NIC; physical address of a machine changes everytime (LocalTalk) and a mobile computer can move from one physical network to another. 11.What is proxy ARP?

A router represents a set of hosts. When an ARP request seeks the physical address of any host in the set, the router sends its own physical address, This creates a subnetting effect. 12.What is RARP?

Reverse ARP is a form of dynamic mapping in which a given physical address is associated with a logical address. 13. What is the use relay agent in BOOTP?

It is router that helps send local BOOTP requests to remote servers. 14.How many data bases are used in DHCP ?

Static database: to store the permanent IP addresses assigned to hosts. Dynamic database: to store temporary IP addresses. 15.What is reverse mapping?

Mapping physical address to the logical address. 16. What is the need for reverse mapping?

A diskless ststion is just booted and an organization does not have enough IP address. 17. What is IGMP?

Internet group management.IGMP is an integral part of IP layer in all hosts and routers that support multicasting. 18. What is MBone?

Multicast backbone network.The network formed by inter connected set of mrouter. 19.What is autonomous sytem?

A group of networks and routers under the authority of a single administration. 20.What is Interdomain routing?

Routing between autonomous sytems Part – B

1.Explain ARP in detail. 2.Explain BOOTP and DHCP in detail. 3.Explain ICMP in detail. 4.Explain IGMP in detail. 5.Explain Distance vector and Link state routing algorithm in detail. 6. Consider a network using the link state algorithm and assume that router A receives the following link state packets from other routers in the network. LSP from node B C D E

Neighbor node (link cost)

A(4) C(8) D(15) E(6) A(5) B(8) D(1) E(2) B(15) C(1) E(10) A(16) B(6) C(2) D(10) Construct the network topology from this table. From the topology you have constructed, use Dijkstra’s algorithm to compute the shortest path from node A to all nodes in the network. 7.Explain DVMRP in detail. UNIT IV. TRANSPORT LAYER.


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1.How is repeater different from an amplifier?

An amplifier cannot discriminate between the intended signal & noise; it amplifies equally everything fed to it. A repeater does not amplify the signal; it regenerates it; when it receives a weakened or corrupted signal, it creates a copy bit for bit, at the original strength.

2.What is the function of a router?

• • •

Routers are specialized computers, which determine the best path for a particular transmission. Routers operate in the physical, data link, & network layers of the OSI models. Routers relay packets among multiple interconnected networks. They route packets from one network to any of a number of potential destination networks on an internet.

3.What is the function of a gateway?

A gateway is a protocol converter. Gateways potentially operate in all seven layers of the OSI model. • A router by itself transfers, accepts, & relay packets only across a network using similar protocols. • A gateway, on the other hand, can accept a packet formatted for one protocol and convert it to packet formatted for another protocol, before forwarding it. • A gateway is generally software installed within a router.

•

4.What are the most popular routing algorithms?

1. Distance vector routing. 2. Link state routing. 5.What are the X.25 layers? How does each relate to OSI model?

X.25 specifies three layers: 1. Physical layer-It uses X.21 protocol. 2. Frame layer-It uses a bit oriented protocol called LINK ACCESS PROCEDURE, BALANCED (LAPB). 3. Packet layer- It uses packet layer protocol. Figure shows the relationship between X.25 layers & OSI layers 6.Distinguish between the X.25 & Frame relay? Feature X.25

Data rate Error control Flow control Multiplexing Congestion control

Fixed Available Available At the network layer Not necessary

Frame Relay

Bursty Not available Not available At the data link layer Necessary

7. There is no sequence numbers in frame relay. Why?

• • •

Frame Relay is a virtual circuit network. In the virtual circuit network, the relationship between all packets belonging to a message or session is preserved. A single route is chosen between sender and receiver at the beginning of the session. When the data are sent, all packets of the transmission travel one after another along the route. So, there is no sequence numbers in frame relay.

8. ATM multiplexes cells using Asynchronous TDM

a) Asynchronous FDM b) Synchronous FDM

c) Asynchronous TDM d) Synchronous TDM.

9. The VPI of an NNI is 12 bits length. 10.Which is more efficient, circuit switching or virtual circuit switching? Why?

• • •

Virtual circuit switching is more efficient than circuit switching. In circuit switched connection, the links that make a path are dedicated. They cannot be used by other connections. In a virtual circuit connection, the links that make a route can be shared by other connections.

11. What are the three switching methods?

Circuit switching Packet switching andMessage switching.

12. The PSTN is an example of a circuit switched network. 13. What are the two popular approaches to packet switching?

1. The datagram approach. 2.The Virtual circuit approach.


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14.What is the fundamental difference between the circuit switching and packet switching? Feature

Circuit switching

Packet switching

Required Fixed Yes No Yes Required At setup time

Not required Dynamic No Yes No Not needed On every packet

Dedicated copper path Bandwidth available Potentially wasted bandwidth Store-and-forward transmission Each packet follows the same route Call setup When can congestion occur

15.What is meant by virtual path? A virtual path (VP) provides a connection or a set of connections between two switches. Think of a virtual path as a highway that connects two cities. Each highway is a virtual path. 16. What is the major difference between Nonadaptive and adaptive routing Algorithm? • Nonadaptive Routing: In nonadaptive routing algorithm, once a path to a destination

•

has been selected, the router sends all packets for that destination along that one route. The routing decisions are not made based on the condition or topology of the networks. Adaptive Routing: In adaptive routing algorithm, a router may select a new route for each packet (even packets belonging to the same transmission) in response to changes in condition and topology of the networks.

17. What is primary difference between N-ISDN and B-ISDN? S.No N-ISDN

1 2

B-ISDN

Narrowband ISDN Broadband ISDN It supports data rate of 64Kbps to It supports data rate of 600Mbps. 1.544Mbps.

18. Give two differences between connection-oriented and connection-less services. S.No Connection-oriented service Connectionless service

1 2

3 4

It is modeled after the telephone system To use a connection-oriented network service, the service user first establishes a connection, uses the connection, and releases the connection. The packets are delivered from the source to the destination in the correct order.

It is modeled after the postal system To use a connectionless network service, the service user selects the route and sends the packets. There is no connection establishment and termination. The network transfers each packet of data to the destination one at a time, independently of the other packets. Example: Electronic junk mail & Registered mail

Example: Remote login & Digitized voice transmission

19. What is Socket Address?

Socket Address is a combination of IP address and port Address

20. What are the types of Socket

Stream Socket, Packet Socket, Raw Socket PART B

1. What are the advantages of using UDP over TCP 2. Discuss with a neat diagram of UDP Segment 3. Describe the steps required for data communication for a connection oriented protocol 4. Explain about TCP Congestion control in detail 5. Explain the steps involved in computing checksum for an UDP Datagram 6. What is Silly window Syndrome? 7. List and Discuss the states used in the TCP Connection management finite state machine 8. Explain How TCP Flow control works


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9. Explain in detail the various techniques to improve QoS

UNIT V: APPLICATION LAYER 1.Define the term graceful close? It

is the service provided by the session layer to ensure that the data exchange is complete before the session closes. 2.What is the relation between plaintext and ciphertext?

• •

The original message is called plaintext. The encrypted message is called ciphertext.

3. What are the two categories of encryption/decryption methods? What is the main difference between the categories? 1. Conventional methods: In this method, the encryption key and 2.

the decryption key are the same and secret. Pubic key methods: In this method, the encryption and decryption algorithms are completely different functions and the keys are different. Every user has the same encryption algorithm and key. The decryption algorithm and key are kept secret. Anyone can encrypt information, but only an authorized receiver can decrypt it.

4. What is the concept behind substitutional character-level encryption? a. It is a simplest form of character-level encryption. b. In monoalphbetic substitution (Caesar Cipher), character is replaced by another character in the set.

each

c. The monoalphabetic encryption algorithm simply adds a number to the ASCII code of the character; the decryption algorithm simply subtracts the same number from the ASCII code of the character.

5. What is relative compression?

d. Relative compression is the method of reducing the number of bits. It is also called as differential encoding. e. This method is extremely useful for sending video. Commercial TVs send 30 frames of 0s and 1s every second. However, usually there is little difference between consecutive frames. f. So, instead of sending an entire frame, in this differential encoding method only the difference between consecutive frames are sent. g. The small differences can be encoded into small steams of bits.

6.What is statistical compression?

h. Statistical compression is one of the lossless data compression methods. i. This method uses short codes for frequent symbols and long codes for infrequent symbols. In this way, the length of the total data is reduced tremendously. j. The three common encoding systems using this principle are Morse code, Huffman encoding and Lempel-Ziv-Welch encoding.

7.What is run-length encoding?

k. Run-Length encoding is one of the lossless data compression methods. l. When data contain strings of repeated symbols, the strings can be replaced by a special marker, followed by the repeated symbol, followed by the number of occurrences. m. The symbol being repeated is called the run symbol and it follows the marker. The number of occurrences, which is called length, is placed after the run symbol in the compressed data. n. This run-length encoding method can be used in audio and video.


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EC2353 ANTENNA AND WAVE PROPAGATION 8.An example of lossy compression is JPEG

a. Differential encoding c. Run-Length encoding

DEPARTMENT OF ECE

b. Lempel-Ziv-Welch encoding d. JPEG

9.Encryption and decryption are functions of the presentation layer. 10.How is a secret key different from a private key?

The secret key is also called a private key. It is available only with authorized customers who can view their account. 11.In the public key encryption, the private key is u sed for decryption 12.How many keys are needed for a sender and a receiver in secret key encryption?

• • •

Two keys are needed for a sender and a receiver. A sender (customer) uses one public key and one secret key A receiver (the bank) uses one secret key and one public key

13. How do authentication and access authorization differ?

• •

Authentication means verifying the identity of a sender. This technique tries to verify that the message is coming from an authentic sender and not an imposter. Access authorization is that the host gives permission only to users who have valid details.

14.Which factors needed for a secure network are handled by the digital signature? • The concept of digital signature is similar to that of signing

•

transaction document when we do business with a bank. In network transactions we cannot personally sign the request for withdrawal. However we can create the equivalent of an electronic or digital signature by the way we send the data.

15.What are the objectives of CMIS?

Fault management, Accounting management, Configuration and name management, Performance management, Security management 16.What are the specific services provided by CMISE ?

Management association services , Management notification services, Management operation services 17.What are the classifications of Encryption methods?

• •

Encryption methods fall into two categories 1. Conventional methods 2. Public key methods Conventional method can be classified into two types 1. Character-level encryption 2. Bit-level encryption

18.What is the use of mail transfer agent?

•

• • •

A Message Handling system has two subsystems. 1. User Agent: It allows people to read and send email. 2. Message or Mail transfer agent: It moves the messages from source to destination. The user agents are local programs that provide a command-based, menu-based or graphical method for interacting with the email system. The mail transfer agents are typically system daemons that run in the background and move email through the system. MTAs are like the different departments of a post office.

19.What is a virtual terminal and how is it used in remote access?

• •

A virtual terminal is an imaginary terminal with a set of standards characteristics that every host understands. It is a software version of a physical terminal. A terminal that wishes to communicate with a remote host communicates to its local host. The local host contains VT software that translates the request or data received from the actual terminal into the intermediary format used by the virtual terminal.


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• •

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The reformatted data travel over the network to the remote host. The remote host passes the transmission to its own VT software, which transforms it from its VT format into the format used by the remote host’s own terminals. Therefore the remote host receives the input as if from a local host.

20.What is Digital Signature?

Digital signature is basically authentication technique based on public key encryption/decryption.

21.What is cryptology?

The art of devising ciphers (Encryption) and breaking (Decryption) them is collectively known as cryptology.

22.List the services offered by the session layer. • To coordinate connection and disconnection of dialogs between applications. • To provide synchronization points for data exchange. • To coordinate who sends when. • To ensure that the data exchange is complete before the session closes.

1. 2. 3. 4. 5. 6. 7. 8. 9.

PART B

Explain RSA in detail with an example With neat diagram explain DES Algorithm in detail Write short notes on i) FTP ii) HTTP iii)SMTP Explain the followings related with FTP i) Connections and communications ii) Commands Explain the followings related with HTTP i) Messages ii) Headers List and discuss the different types DNS Records With Relevant example discuss Substitution Ciphers Explain the different types of Authentication Protocols What is the need of Digital Signature? Explain the different types to generate Digital Signature


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ST. JOSEPH`S COLLEGE OF ENGINEERING QUESTION BANK SUB: PRINCIPLES OF MANAGEMENT SUB CODE : MG 2351 BRANCH: ECE SEMESTER – VI UNIT – I Part A (Each question carries 2 marks) 1. Define Management. Management is the process of designing and maintaining an environment in which individuals, working together in groups, accomplish their aims effectively and efficiently. According to Koontz and Weilhrich "Management is process of designing and maintaining of an environment in which individuals working together in groups, efficiently and efficiently attain the organizational goals." State the Functions of Manager. 2. P – Planning O – Organising S – Staffing D – Directing CO – Coordinating R – Reporting B – Budgeting 3. What are the various skills required by a manager? Managers require three kinds of skills Technical Skill – Knowledge of and proficiency in working with tools and technology Human Skill – Ability to work with people Conceptual Skill – Ability to recognize important element in a situation and understand relationship among elements Write some characteristics of Management 4. Management is a continuous process. 2) Managers use the resources of the organisation both physical as well as human to achieve the goals. 3) Management aims act achieving the organisation goals by ensuring effective use of resources. Define Productivity. 5. It implies effectiveness and efficiency in individual and organizational performance. Productivity = Outputs Inputs (within a time period, quality considered) What is Effectiveness & Efficiency ? 6. Effectiveness is the achievement of objectives and Efficiency is the achievement of the ends with the least amount of resources. Effectiveness is doing right things & efficiency is doing things rightly. 7. What are management levels? Top level management. 2) Middle level management. 3)Lower level management. Write some important functions of top level management . 8. To formulate goals and policies of the company. 2) formulate budgets. 3) To appoint top executives.


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9.

What is social responsibility?

interest 10.

DEPARTMENT OF ECE

Social responsibility is the part of the management to initiate actions to protect the

of the society. Write Fayol's fourteen principles of management .

1) Division of work. 2) Authority and Responsibility. 3) Discipline. 4) Unity of command. 5) Unity of direction. 6) Subordination of Individual interest to general interest. 7) Remuneration. 8) Centralisation 9) Scalar chain. 10) Order. 11) Equity. 12) Stability of Tenure. 13) Initiative. 14) Esprit de Corps.

11.

What is scalar chain?

12.

Explain: Management is both —A science and an art.

13.

What is Esprit-de-corps?

14.

List out the claimants of the business enterprise.

The instructions and orders should be sent from the top management to the lower management.

Management is a science because it contains general principles. It is also an art because it requires certain personal skills to achieve desired results. It means ‘Unity is strength’ In an organization, amongst the employees there should be harmony and unity.

1) Shareholders. 2) Employees. 3) Customers. 4) Creditors. 5) Suppliers. 6) Government

15.

What are the major contributions of Taylor?

16.

Write some important functions of top level management.

top 17.

the 18.

19.

The major contributions of F.W.Taylor are as follows • He developed the principle of division of labor/work • He developed method study • He advocated time study • He developed certain principles to breakup each job into small independent elements • He developed the concept of fair day’s work • He proposed the functional organization

To formulate goals and policies of the company. 2) formulate budgets. 3) To appoint executives. What is time study?

Time study refers to the measuring of (under controlled conditions) the time for completing a particular process using specific materials and techniques. This will be useful in arriving at a scientific standard for each work task in marketing process. Define partnership

Under the Indian Partnership Act of 1932, Partnership is defined as – relation between persons who have agreed to share the profits business carried on by all or by any one of them acting for all”. What do you mean by ‘unity of command’?

‘Unity of command’ is an important principle proposed by Henry Fayol. implies that an employee should receive orders from one superior 20. What is centralization ?


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The organization is centralized when the power is concentrated in the hands of few

Part B(Each question carries 16 marks)

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Explain the Functions of Management. Discuss whether Management is a Science or Art. Explain Systems approach to Operational Management. Explain the Henry Fayol’s principles of management? Explain the contributions of FW Taylor. Explain forms of business organizations. State the characteristics of a company. Differentiate between public limited company and private limited company. Discuss partnership firm, it characteristics , types., advantages and disadvantages. Explain the evolution of management thought.

UNIT – II Part A (Each question carries 2 marks) 1. Definition of planning

2.

The determination of what is to be done, how and where it is t be done, who is to do it and how results are to be evaluated. Types of planning

Short range and long range planning repeated and si ngle use planning and

3.

functional planning What are the Qualities of good plan?

4.

What are Rules ?

5. 6. 7. 8.

9.

10. 11.

Simple , logical, flexible, practical, stable and it must be complete and integrated Statement of expected results expressed in quantitative terms. Define Procedure

It is a series of related task that up the chronological sequence and the established way of performing the work to be accomplished. Define Budget.

Statement of expected results expressed in quantitative terms. Define Objectives.

Objectives are goals established to guide the efforts of the company and each of its components What is MBO ?

Process where by the superior and subordinate of an organization jointly identify its common goal, define each individual’s major areas of responsibility in terms of results expected of him and use this measures as guides for operating the unit and assessing the contribution of each if its members what is TOWS matrix ?

It is a conceptual frame work for systematic analysis, which facilitates matching the external threats and opportunities with the internal weakness and strength of the organization. Define Strategy.

Determination of basic long term objectives and of courses of action and allocation of resources to achieve these aims. What are Policies ?


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12. 13.

14 15. 16.

Verbal, written, or implied overall guide setting up boundaries that supply the general limits and direction in which managerial action will take place. State different strategies of Porter’s generic strategy. Overall cost leadership strategy, differentiation strategy and focused strategy Define Planning Premises.

Anticipated environment in which plan are expected to operate. They include assumptions or forecasts of the future and known conditions that will effect the operation of plans Define MIS

MIS is more advance technology for solving its basic requirements. MIS used for decision making in the various functional areas of business. Explain the terms decision-making.

It is a process of selection from a set of alternative courses f action which is thought to fulfill the objectives of the decision problem more satisfactory than others. What are the difference between PERT and CPM

S. No. 1. 2. 3. 4.

CPM It is activity oriented CPM is planning device It estimates only one time It is a deterministic model

17

What are classification of budget?

18.

What is zero base budget?

19.

What is DSS ?

20.

DEPARTMENT OF ECE

PERT PERT is event oriented It is control device It estimates three times It is probabilistic model

a) Functional classification- Sales, production, cash, capital and master budget b) Time classification- Short, current and long term budget c) Activity level- Fixed and flexible budget

Initially the budget is designed from a zero base. The main element is ZBB is future objective orientation. DSS –use computers to facilitate the decision making process of semi structured tasks Benefits of planning

Emphasis on objectives, minimizes uncertainty, facilitates control, improves coordination, secure economy, encourage innovation and improve competitive strength

Part B (Each question carries 16 marks)

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Discuss the Nature of Planning. Explain the Steps in Planning. Explain Various elements of Plans . Explain Purpose of Planning. Explain the Process of MBO. Discuss the Advantages and Disadvantages of MBO. Explain Strategic Planning Process. Explain Tows Matrix. Explain Portfolio Matrix. Suggest some recommendations to make strategies successful.

UNIT III


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1.

DEPARTMENT OF ECE

Define Organizing?

Organising is the process of identifying and activities required to attain the objectives, delegating < creating responsibility and establishing relationships I people to work effectively.

2.

Mention any four characteristics of an organization.

3.

List out the steps involved in organization process.

a. b. c. d.

Common objectives Specialisation or Division of Labour Authority of structure Group of persons

a. Determination of activities b. Grouping of activities c. Assignment of Duties d. Delegation of authority

4.

Mention the various principles involved in organization.

1. Principle of unity of objective 2. Principle of division of work or specialization 3. Principle of efficiency 4. Principle of span of control

5. Differentiate between formal and informal organization.

SI no. Point of view

Formal organisation

Informal organisation

1.

Origin

It is created spontaneously naturally.

2.

Purpose

3. 4.

Nature Size

It is created deliberately and consciously by the frames of the or anisation. It is created for achieving legitimate objectives of the or anisation. Planned and official It may quite large.

It is created by members of the organisation for social and s cholo ical satisfaction.

Unplanned and unofficial.

6.

It may be small size. Mention the three categories of relationships in span of management.

7.

State the important factors in determining an effective span of management.

a. Direct single relationship relationships c. Cross relationship

b. Direct group

1. Capacity of superior 2. Capacity of subordinates 3. Nature of work 4. Type of technology 5. Delegation of authority 8.

What are the types of departmentation ?

1. Departmentation by function. 2. Departmentation by Territory or Geography. 3. Departmentation by Customers. 4. Departmentation by equipment or process.


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5. Departmentation by product or service. 9.

State the advantages of departmentation by function. Advantages:

1. It is most logical, scientific, time proven and natural method of departmentation. 2. It provides specialization of work which makes maximum utilization of manpower and other resources. 3. It ensures proper performance control. 4. It facilitates delegation of authority and therefore, reduces the burden of top executives. 10.

State the disadvantages of departmentation by function. Disadvantages:

1. There is a tendency for overspecialization. The department managers are experts in handling the problems in their department alone. They may not be able to understand the problem of other departments. 2. Functional departmentation discourages communication across functions so that the workers develop a narrow technical point of horizontal conflicts. 3. It increases the workload and responsibility of the departmental heads. 4. It does not offer any scope for training for the overall development of manager.

11.

Give a note on departmentation by customers.

This type of departmentation is preferred when the needs of customers are different in nature. Big organizations provide special services to different types of customer.

12.

What is departmentation by product?

Departmentation By Product Or Service: In this case, the units are formed according to the product. It is more useful in multi-line corporations where ] expansion and diversification, manufacturing and mark characteristics of the product are of primary concern. 13.

Define authority. "Authority is the right to give orders and the power to exact obedience".

14.

15.

List out the sources of authority.

a. Formal authority theory c. Competence theory

18.

What is line authority?

Line authority is the direct authority which a superior exercises over a number of subordinates to carry out orders and instructions. In an organizing process, authority is delegated to the individuals to perform the activities.

16.

17.

b. Acceptance Authority Theory , ;

What is staff authority?

A staff person assists the line people in attaining their objectives. Staff authority is purely advisory. Types of staff authority are a) Advisory staff authority, b) Compulsory staff authority & c) Concurrent staff authority. State the types of organizational charts.

a) Vertical or Top-to-Bottom chart b) Horizontal or Left-to-right chart c) Circular or concentric chart

What is departmentation by process?

Departmentation By Process Or Equipment: Under this type of departmentation, activities are grouped on the basis of production


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19.

20.

DEPARTMENT OF ECE

processes or equipment involved. What is Performance Appraisal? What are the different methods/techniques of Performance appraisal?

Performance Appraisal is evaluating the actual performance of the employee for determining the compensation and identifying the potential of the employees. Methods/Techniques of Performance Appraisal: (i) Trait-based appraisal: (job knowledge, leadership, judgment, ability, initiative, loyalty): Graphic scale method, ranking method, grading system, forced distribution method, check list method, Critical incident method, group appraisal (ii)Appraisal by results: MBO, Behaviorally Anchored Rating(BARS), Assessment Centre, 360 degree performance appraisal.

What are various stages of staffing Process? External environment Enterprise plans

Organization plans

Number and kinds of managers required

External sources Recruitment Selection Placement Promotion Separation

Analysis of present and future needs for managers Internal sources

Appraisal Career Strategy Training &Develop ment

Manager inventory


1. 2. 3. 4. 5. 6. 7. 8.

10. 11.

What are the factors determining span of Management? What are the various types of departmentation? Discuss the factors determining the degree of decentralization of Authority. What are various problems in organizing? What are the various factors affecting staffing. Describe Selection Process. What are Methods of Performance Appraisal ? Describe departmentation by process and state its advantages and disadvantages? Distinguish between formal and informal organization. Explain the various sources of recruitment. What are their advantages and disadvantages?

UNIT – IV Part A (Each question carries 2 marks)


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1.

DEPARTMENT OF ECE

Define Leading.

it is a process of influencing people so that they will contribute to organization and group goals. 2. Define Motivation . It is a process of stimulating people to action to achieve/ accomplish desired goals. 3. . Democratic leader He consults with subordinates on proposed actions and decisions and encourages participation from them. .4. Define Job Enrichment. it attempts to make a job more varied by removing the dullness associated with performing repetitive operations 5. What is QWL? Increasing productivity and reducing inflation and as a way of obtaining industrial democracy and minimizing labor disputes. 6. Define Leadership. Art or process of influencing people so that they will strive willingly and enthusiastically towards achievement of the goal . 7. What are the Styles of Leadership ? Autocratic,Democratic and Free-rien 8. Define Communication. Transformation of ideas from one person to another. 9. What are the various types of communication? Formal,informal,vertical,horizontal,grapevine,written and oral communication. 10. Country club management Mangers have little or no concern for production. but are concerned for people 11. Define Motivation It is a process of stimulating people to action to achieve/ accomplish desired goals. 12. Explain - Maslow’s Needs. Physiological needs, Safety needs, Social needs, Self- Esteem needs and Selfactualization needs. 13. Define Incentives An incentive is something which stimulates a person towards some determination 14.what are Job content factors Achievement, advancement, responsibility, respect, growth and development. 15. Define Expectancy theory force=Valance * Expectancy 16. what is Equity theory Outcomes by a person Outcomes by another person ------------------------------------ = ----------------------------------Inputs by a person inputs by another person 17. Define.Creativity Ability and power to develop new ideas 18. what is Innovation. Use of new ideas. 19. Define Brainstorming Improve problem solving by finding new ideas and unusual solution 20.. Define Leadership


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Art or process of influencing people so that they will strive willingly and enthusiastically towards achievement of the goal Part B (Each question carries 16 marks ) 1. Explain some of theories of Motivation? 2. Explain Likert’s Four System of Management. 3. Explain Managerial Grid. 4. Describe Communication Process. 5. What are the Barriers in communication and how they can be improved ? 6. What are the qualities required for effective leadership? 7. what are the essentials of good communication system? 8. Explain the various theories of Leadership? 9. what are the various types and networks of communication? 10. What are the various techniques of Motivation? UNIT - V Part A (Each question carries 2 marks) 1. what is control?

Control is the measurement and correction of performance in order to make sure the enterprise objectives and the plans devised to attain them are accomplished.

2. Give some critical points standards of control.

Cost standard, revenue standards, goals standards and program standards.

3. What is concurrent control?

This control measures for taking corrective action while any programme meet any obstacle in this activities.

4. State the difference between feedback and feed forward control technique?

Feedback

Feed forward

2.

It measures only the output of the process It is submissive approach

3.

Less benefit

It measures the input of the process It is aggressive approach More benefit

S.No. 1.

5.

Define Budget?

6.

Define budgetary control?

7.

Write the objectives of budgetary control?

8.

What are classification of budget?

9.

A Budget the expression of a firm’s plan is financial form for a period of time in to the future.

A system which uses budgets as a means of planning and controlling all aspects of producing and selling commodities and services. d) It aims at maximization of profits e) To plan and control the income and expenditure of the organization f) To provide adequate working capital g) Functional classification- Sales, production, cash, capital and master budget h) Time classification- Short, current and long term budget i) Activity level- Fixed and flexible budget

What is zero base budget?


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Initially the budget is designed from a zero base. The main element is ZBB is future objective orientation. 10. What are the difference between PERT and CPM

S. No. 1. 2. 3. 4.

CPM It is activity oriented CPM is planning device It estimates only one time It is a deterministic model

PERT PERT is event oriented It is control device It estimates three times It is probabilistic model

11. Define MIS

MIS is more advance technology for solving its basic requirements. MIS used for decision making in the various functional areas of business.

12. Define productivity?

Productivity is a measure of how much input is required to produce a given output.

13.

Define OR?

14.

Define Linear Programming?

OR is a systematic analysis of a problem through scientific methods, carried out by appropriate specialists, working together as a team, finding an optimum and the most appropriate solution to meet the given objective under a given set of constraints. It is a mathematical technique in operation research and a plan of action solve a given problem involving linearly related variables in order to achieve the laid down objectives in the form of minimizing or maximizing the objective function under given set of constraints.

15. What is Inventory Control

Inventory control refers to the control of raw materials and purchased material in store and regulation of investment in them.

16. What is JIT ?

Just in time inventory system, in this method the suppliers delivers the materials to the production spot just in time to be assembled. This method reduces the cost of inventory.

17. What are objectives of value engineering?

a) b) c) d) e)

18.

19.

20.

It is a special type of cost reduction technique. Modify and improve product design Reduce the product cost Increase the profit Simplify the product

What is MNC?

Multinational corporation is an enterprise which own or control production or service facilities outside the country in which they are based. Write some advantages of MNCs?

f) It can promote quality product at low price g) MNC leads to increase in production aggregate employment, exports and imports of the required inputs h) It increases the government revenues.

What is work simplification?

It is the process of obtaining the participation of workers in simplifying their work through time study, motion study, work flow analysis and layout of work situation.


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21. Define quality circles?

Quality circles are groups of people, from the same organizational area, who meet regularly to solve problems they experience at work. Members are trained in solving problems, in applying statistical quality control and working in groups.

22. What is preventive control?

It the method to develop better managers who will skillfully apply concepts, techniques and principles and who will look at managing the problems from system point of view, thus eliminating the unwanted results caused by poor management.

23.. What are the various forms of international business?

Exportation, licensing agreement, management contracts, Joint ventures and subsidiaries.


1. 2. 3. 4. 5. 6. 7.

Discuss the Control Techniques. Explain Operations Research Procedure. What are Techniques for improving productivity? Discuss the Principles of Preventive Control. Explain the Global Theory of Management. What factors affect the Companies at International Level? Why do companies decide to go international? Also explain the merits and limitations of multinational companies. 8. Explain how companies go international and also explain how they effect organization complexity and managerial involvement abroad. 9…..Explain the functions of management at international level. 10 . Discuss the various types of budgets


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ST. JOSEPH’S COLLEGE OF ENGINEERING, CHENNAI-119 DEPARTMENT OF ECE EC2354: VLSI DESIGN UNIT I: CMOS TECHNOLOGY PART-A What are the advantages of SiO2 as a dielectric.

SiO2 has a relatively low loss & high dielectric strength, thus application of high gate fields is possible. 2.

State the 3 modes involved in the operation of an enhancement transistor

3.

What is a field induced junction?

4.

1. Accumulation mode 2.Depletion mode 3. Inversion mode.

In a pn junction the n- type conductivity is brought about by a metallurgical process, ie the electrons are introduced into the semiconductor by the introduction of donor ions. In an inversion layer substrate junction, the n- type layer is induced by the electric field E applied to the gate .Thus this junction instead of being a metallurgical junction is a field induced junction. What are the factors that influence the drain current.

• • • • • • 5.

The distance between source and drain The channel width The threshold voltage Vt The thickness of the gate – insulating oxide layer The dielectric constant of the gate insulator The carrier(electron or hole) mobility, µ.

Define cut – off and saturated regions in the characteristics of an MOS transistor.

Cut – off current flow is essentially slow. Saturated region – Channel is strongly inverted and the drain current flow is independent of the drain – source voltage. 6.

Define threshold voltage and state the parameters on which it is dependent on.

7.

Define Body effect.

Vt can be defined as the voltage applied between gate & source of an MOS device below which Ids effectively drops to zero. It is a function of • Gate conductor material • Gate insulation material • Gate insulator thickness - channel doping • Impurities at the silicon insulator interface • Voltage between the source and the substrate,Vsb.

• • 8.

What is channel length modulation?

• • 9.

The threshold voltage Vt is not constant with respect to the voltage difference between the substrate and the source of the MOS transistor. So, when several MOS devices are connected in series, the threshold voltage is increased due to voltage difference between the substrate and the source. This effect of body or substrate voltage is called body effect. When an MOS device is in saturation, the effective channel length is decreased such that, L eff = L - Lshort . Where Lshort = √ 2(εsi /qNa) (Vds – (Vgs – Vt)) The reduction in channel length increases the W/L ratio, thereby increasing β as the drain voltage increases.

Define noise margin. Illustrate how it can be obtained from the transfer characteristics of a CMOS Inverter.

Noise margin is a parameter that allows us to determine the allowable noise voltage on the input of a gate so that the output will not be affected. The 2 common parameters are N MH & NML Where NML = | VILmax – VOLmax| and NMH = | VOHmin – VIHmin| VIHmin=minimum HIGH input voltage VILmax = maximum LOW i/p voltage VOHmin = minimum HIGH o/p voltage


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VOLmax = maximum LOW o/p voltage 10. Define rise time( tr ).

Tr is the time for a waveform to rise from 10% to 90% of its steady state value.

11. Define fall time ( tf )

Time for a waveform to fall from 90% to 10% of its steady state value. 12. Define delay time,td.

Time difference between input transition and 50% output level .This is the time taken for a logic transition to pass from input to output. Fig 4.18 (a) Page 207 Weste. 13. What is latch-up?

Latch-up is the shorting of the VDD & VSS lines in CMOS fabrication process due to parasitic circuit effect. Latch-up results in chip self-destruction or system failure. 14. How is a capacitor created in CMOS fabrication process?

Capacitors are created in the CMOS fabrication process by adding at least one extra layer of polysilicon. Between the two polysilicon layers, a second thin-oxide layer is required. 15. List the materials used for masks in IC technology.

Photoresist, Polysilicon, Silicon dioxide,Silicon nitride 16. What are the advantages of twin tub process?

Used for protection against latch-up Provides separate optimization of p-type & n-type transistors 17. How is resistor created in CMOS fabrication process?

If Polysilicon is left undoped, it is highly resistive. This property is used to build resistors. A resistive metal such as nichrome me be added to produce high value & high quality resistors. The resistor accuracy might be improved by laser trimming the resulting resistors on each chip to some predetermined test specification. 18. What is BiCMOS?

BiCMOS is the combination of bipolar & CMOS transistors. To reduce the delay times of the highly loaded signals (microprocessor busses) and to provide better performance for analog functions the bipolar devices (npn or pnp) can be added to MOS transistors or vice versa. 19. What are the advantages of SOI process?

There is no latch-up There are no body-effect problems No field-inversion problems Lower substrate capacitances provide the possibility for faster cirecuits. 20. What is the objective of the layout rules?

To obtain a circuit with optimum yield in as small an area as possible without compromising reliability of the circuit. 21. What are the types of layout design rules?

•

Micron rule,Lambda based rule

22. What is guard ring?

p+ diffusion in the P-substrate and n + diffusion in the n-well are called guard rings that are used to collect injected minority carriers. When they are implemented in a structure, the n + guard ring must be tied to VDD and the p + guard ring must be connected to VSS. Guard rings must be included in the fabrication process to prevent I/O latch-up. 23. What is scribe line?

The scribe line is a specifically designed structure that surrounds the completed chip and is the point at which the chip is cut with a diamond saw. The construction of the scribe line varies from manufacturer to manufacturer. 24. What is passivation or overglass?

•

This is a protective glass layer that covers the final chip. Openings are required at pads and any internal test points.

25. List the two techniques that can be used to prevent latch-up

•

Latch-up resistant CMOS process,Layout techniques

26. What are the types of oxidation?


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Wet Oxidation: The oxidizing atmosphere contains water vapor Dry Oxidation: The oxidizing atmosphere is pure oxygen

27. What are the advantages of EBL pattern generation?

EBL: Electron Beam Lithography Patterns are derived directly from digital data There are no intermediate hardware images Different patterns may be accommodated in different sections of the wafer without difficulty. Changes to patterns can be implemented quickly. 28. What are the types of etching process?

•

Isotrophic etch,Fully anisotrophic etch,Preferential etch

29. What are the types of interconnect?

Metal interconnect Polysilicon/Refractory interconnect Local interconnect 30. What is a thinox ?

Thinox is an active mask formed which defines the areas where thin oxide are needed to implement transistor gates and allow implantation to form P or N-type diffusions for transistor source/drain regions. 31. How is the channel stop implant made?

Channel stop implant is made by doping the P-substrate in areas where there are no N-transistors P + using a photo resist mask. 32. List the four main CMOS technologies

i. N-well process ii.P-well process iii. Twin-tub process iv. Silicon on insulator. PART-B

1. (a) Explain the operation of a CMOS inverter clearly indicating the various regions of operation.(12) (b) List the advantages of Lambda based design rules as compared to micron based design rules.(4) (Apr’05) 2. (a).Discuss the aspects of MOS transistor threshold voltage.(8) (b) Derive the VTC of CMOS inverter. (8) (Apr’05) 3. (a). Discuss the operation of s CMOS inverter with diagrams.(8) (b) Discuss the mead Conway design rules for the silicon gate NMOS process.(8) 4. Briefly describe the working principles & characteristics of NMOS device with necessary diagrams.(16) (Nov ’04) 5. Explain the various steps involved in the P-well CMOS process with necessary diagrams (Nov ’04) 6. (i) Draw and explain the n-well process (10) (ii) Explain the twin tub process with a neat diagram (6) (Nov’07) 7. (i) Discuss the origin of latch up problems in CMOS circuits with necessary diagrams. Explain the remedial measures. (10) (ii) Draw and explain briefly the n-well CMOS design rules. (6) (Nov’07) 8. Explain the various features of CMOS technology (May 09) 9. Discuss the steps involved in IC fabrication process (16) (Nov09) 10. Describe n- well process in detail (16) (Nov 09) 11. Explain with neat diagrams the SOI process and mention its advantages. 12. i) How are circuit elements implemented in IC’s? (8) ii) Explain about CMOS interconnects with diagrams (8) (Nov 08) 1.

UNIT II:CIRCUIT CHARACTERIZATION AND SIMULATION PART-A What are critical paths ?

2.

List the levels affecting critical path.

Critical paths are logic paths that require attention to timing details. Designers use a timing analyzer to find the slowest path in a logic design. Quick delay estimation is essential to design critical paths.


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The architectural / micro architectural level, the logical level, the circuit level, and the layout level. 3.

Why floor planning is of great importance in VLSI?

Delay is dependent on the layout. The floor plan determines the wire lengths that can dominate the delay. 4.

What is propagation delay time tpd?

It is the maximum time from the input crossing 50% to the output crossing 50%. It is also called as Max-time. 5.

What is contamination delay time tcd?

6.

What are the depending factors for delay of a logic gate?

It is the minimum time from the input crossing 50% to the output crossing 50%. It is also called as Min-Time. a. Width of the transistors in the gate. b. Capacitance of the load that must be driven.

7.

How do you determine gate and diffusion capacitance?

Gate capacitance can be determined from the transistor width form the schematic and diffusion capacitance depends on the layout. 8. Give the equation for elmore delay model. N

N

t pd= ∑ R n-i Ci = ∑ Ci ∑ R j i

i=1

j=1

R n-i = Node in the ladder of resistance R n-i between the node and a supply. 9.

Define logical effort.

Logical effort is defined as the ratio of input capacitance of the gate to that of the input capacitance of an inverter that can deliver the same output current. It is independent on the size. It helps to estimate the delay of the entire path quickly based on the parasitic and logical delay of the path. 10. What is electrical effort?

It is the ratio of load capacitance to input capacitance. It is also called as the fan-out. This depends on the size. 11. What is parasitic delay?

The parasitic delay of the gate is the delay of the hate when it drives zero load. It can be estimated with RC delay models. 12. Give the equations that express the delay of a logic gate.

d= f + p , p=> Parasitic delay, f => Effort delay/ Stagg effort f d= g.h , g => Logical effort , h=> electrical effort/Fan-out h=Cout / Cin, Cout => Capacitance of the external load being driven. Cin=> Input capacitance of the gate.

13. What is path delay?

It is the sum of delays of each stage. It is the sum of the path effort delay D f and path parasitic delay P. D= Σ di = Df + P , where Df = Σ fi & P= Σ Pi 14. Give the factors that give rise to static power dissipation.

a. b. c. d.

15.

Sub-threshold conduction through off transistors. Tunneling the current through gate oxide. Leakage through reverse biased diodes. Contention current in the ratioed circuits. Give the factors that produce dynamic power dissipation. a. Charging and discharging of load capacitance. b. Short term current when both PMOS and NMOS networks are partially ON .

16. Give the formula for static power dissipation

Pstatic = Tstatic VDD

17. Write the formula for dynamic power dissipation.

Pdynamic=C VDD2 f sw C=> Load capacitance VDD=> High potential / power f sw => average frequency


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18. How do we reduce dynamic power?

Activity for reduction, Reduction of the inter connect switching capacitance and Choose lower power supply /operating frequency.

19. What is wire pitch?

The sum of the width and the spacing from their neighbors is called the wire pitch. 20. What is aspect ratio?

The thickness to width ratio is called aspect ratio. 21. What is cross talk?

In modern VLSI processors, transistors switch much faster. The wires are packed very closely together and thus a large fraction of their capacitance is to their neighbors. When one wire switches, it tends its neighbor through capacitive coupling. This effect is called cross talk. 22. Why does interconnect increase delay?

1. The wire capacitance adds loading to each gate. 2. Long wires have significant resistance that contributes distributed RC delay or flight time. 23. List the hard errors that cause integrated circuits to fail permanently.

Electro migration, Self heating, Latch up, Overvoltage failure, Circuit pitfalls

24. What is MTBF and FIT?

MTBF is the mean time between failures. FIT is the failure in time, the number failures that would occur every thousand hours per million devices.

25. What is infant mortality?

Soon after birth, systems with weak or marginal components tends to fail. This period is called infant mortality. 26. What are the effects of self heating?

1. Hot wires exhibit greater resistance and delay. 2. Self-heating causes temperature induced electro migration problems in 3. Brief pulses of high peak currents may even melt the inter connect.

bidirectional

wires.

27. What do you mean by latch up in CMOS technology?

CMOS chips develop law resistance path between V DD and GND causing catastrophic melt down. The phenomenon called latch up occurs when parasitic bipolar transistor formed by the substrate well and diffusion turn on. With proper layout procedures latch up problems can be easily avoided. 28. Give the types of scaling in CMOS technology.

Transistor scaling,

Interconnect scaling

29. What do you mean by SPICE?

SPICE is a Simulation Program with Integrated Circuits Emphasis. It solves the non linear differential equations describing components such as transistors, capacitors and voltage sources.

30. What does the two letters in units denote in SPICE?

The first character indicates the order of magnitude and the second letter indicates a unit for human convenience and is ignored by SPICE. 31. What is threshold voltage?

The threshold voltage is defined as the values of V gs below which Ids becomes zero. In the real transistor characteristics, sub-threshold current continues to flow for Vgs < Ids. The threshold voltage varies with L,W, Vds and V bs . PART B

1. Discuss in detail about the various delay models in CMOS technology. 2. What is meant by power dissipation? Derive an expression for static power dissipation and dynamic power dissipation. 3. Explain interconnect in detail. 4. Explain in detail about Device models. 5. Discuss in detail about hard errors and soft errors in VLSI technology? 6. Write notes on logical effort and transistor sizing. 7. Explain low power design. 8. Explain the various circuit pitfalls that cause chips to fail. 9. Find the rising and falling propagation delays of an AND- OR- INVERT gate using the Elmore delay model. Estimate the diffusion capacitance based on a stick diagram of the layout. 10. Draw a 3- input NAND gate with its gate and diffusion capacitance. Assume all diffusion nodes are contacted.


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UNIT III: COMBINATIONAL AND SEQUENTIAL CIRCUIT DESIGN PART-A What is a transmission gate.

A transmission gate consists of an n- channel transistor and a p – channel transistor with separate gate connections and common source and drain connections. It gives good transmission of both logic 1 and logic 0. 2. Why is the transmission of logic 1 degraded as it passes through a nmos pass transistor.

When S = 1 (Vdd) , and Vin = 1 the pass transistor begins to conduct and charges the CL towards Vdd.Initially Vin is at ahigher potential than Vout, the current flows through the device. As voltage ot the load approaches Vdd – Vtn, the n- device begins to turn – off. Vtn is the n- transistor body effected threshold .. Thus the transmission of logic 1 is degraded. 3.

What is a tristate inverter.

A tristate inverter is got by cascading a transmission gate with an inverter. When c = 0 and –c = 1, the output of the inverter is in a tristate condition. 4.

Draw the structure & symbol of a CMOS tri - state inverter.

5.

Write the equation for total static power dissipation.

n Ps = ∑ leakage current X supply voltage 1 n = no: of devices. 6.

What is a pass transistor ? What are its advantages ?

7.

How latch up problems can be rectified in CMOS fabrication process ? (Nov ’04)

Pass transistor is similar to a buffer. Advantages of pass transistor are (i) occupies less space,because any logical operation can be realized with lesser number of MOS transistors (ii) No direct path between VDD and Gnd. So,amount of power dissipation is lesser under stand by condition.

CMOS/bulk devices have parasitic bipolar transistors can cause latch up,a condition in which high currents exist between VDD & Gnd. One method of preventing Latch up consists of decreasing the current gains of the parasitic transistors. If the product of the two current gains of both transistors is less than unity, f/b is not self sustaining & the device cannot latch. The current gain of the vertical pnp tr is determined by the process design & can be reduced by using buried layers of n+ material under the n wells. The tendency of CMOS / bulk devices to latch up is reduced by putting guard rings around the p&/or n wells & making frequent contacts to the rings. This reduces the parasitic resistance values. 8.

What is a transmission gate ? Realize a 2-input XOR gate using transmission gates. (Apr ’05)


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What is a pull – down device (nov 09)

10. What are the disadvantages of CMOS transmission gates? Draw the symbol for transmission gate.

Disadvantages of CMOS transmission gate are (iii) Require more area than NMOS pass circuits (iv) Require complemented control signals T.G symbol

11. Give a brief description about NAND implementation of a MUX circuit.

MUX consists of switched paths.NAND implementation uses depletion devices to short circuit undesired connections while using enhancement mode devices to form the switches that exert control. MUX is defined by the locations of the ion implants required to form the depletion mode transistors. (1) Diagram (1) A’

A

B’

B

I0 I1

I2 I3


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12. Draw the structure of 2:1 CMOS MUX.

13.

14.

15.

What is meant by scaling ?

Scaling of MOS transistor is concerned with systematic reduction of overall dimensions of the devices as allowed by the available technology, while preserving the geometric ratios found in the larger devices. Is D-flipflop applicable for counter applications ? Why ?

D-latch is not an edge triggered storage element because the output changes according to the input, ie, latch is transparent, when the clock is high. Due to this transparency property, it is unsuitable for counter applications. List the disadvantages of dynamic logic.

(v) (vi) (vii) (viii) (ix) 16.

17.

Logic function is implemented by the NMOS pull down network. Less no. of transistors required. Noise margin doesn’t depend on transistor ratios Consumes only dynamic power. Faster switching speeds.

What is meant by domino logic ?

Domino logic module consists of a PE logic block followed by an Inverter. This ensures that all inputs to the next logic block are set to 0 after the precharge period. So, only the possible transition during the evaluation period is the 0-1 transition. Draw the switch logic arrangement for CMOS 3-input NOR gate.

18. Draw 2-input MUX gate using transmission gates.


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19. Write down the Expression for the total propogation delay in an n bit carry bypass Adder.

T p = tset up + M tcarry + (N/M-1) t bypass + M tcarry + tsum. 20. What is the total time delay for a ripple carry Adder.

Tadder = (N-1) tcarry + tsum. 21. List the different considerations for designing a Ripple carry adder.

(i) (ii) (iii)

Propogation delay of ripple carry adder is linearly proportional to N. It is important to optimize tcarry than tsum. Inverting all i/ps to a full adder results in inverted values for all o/ps.

22. What are the draw backs of a static adder circuit.

(iv) (v)

Consumes large area. Circuit is slow.

23. Why is static adder circuit slow ?

A static adder ckt is slow as, (i) long chains of series PMOS transistors are present in both carry & Sum generation circuit. (ii) Intrinsic load capacitance of the C o signal is large & consists of 2 diffusion & 6 gate capacitances plus the wiring g capacitances. (iii) Carry generation ckt requires 2 inverting stages per bit. (iv) Sum generation ckt requires an extra logic stage

24. What is the advantage of Dynamic adder design?

Reduced capacitance of dynamic circuitry results in substantial speed up over static implementation.

25. List the advantages of two phase clocking scheme.(Nov ’04)

(i)No chance of race conditions occurring in the circuit (ii) No timing errors due to races or Hazards or clock skew (iii) two phase clocking schemes are popular due to its simplicity & reliability (iv)Design procedures are also simple PART B

1. What is a pass transistor ? What are their limitations ? Why ? Explain how transmission gates are built and their principle of operation. (16) (Apr ’05) 2. Construct a 8 to 1 multiplexer using CMOS devices. Give necessary explanation.(8) 3. Explain why the transmission gate of logic 1 is degraded as it passed through a n MOS pass transistor (4) (Apr ’05) 4. Explain Pass Transistor and transmission gates with neat sketches. (8) 5. Design CMOS NOR gate, NAND gate and NOT gate. 6. Discuss the operation of a CMOS latch (6) (Nov’07) 7. Implement the following function using CMOS f(A,B,C) = A’BC + AB’C + ABC’ (8) 1.

UNIT IV: CMOS TESTING PART-A List some typical defects in the manufacturing of IC.

• Layer to layer shorts • Discontinuous wires • Thin – oxide shorts to substrate or well. • Nodes shorted to ground or power


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• Nodes shorted to each other • Inputs floating • Outputs disconnected 2.

What are SA0 & SA1 faults.

When anode in a circuit is permanently at logic 1 or 0 due to thin oxide shorts , ie the n – transistor gate to Vss or the p – transistor gate to Vdd or meta to metal shorts. The SA0 or SA1 Fault occurs. 3.

Define observability and controllability.

4.

What is fault sampling?

Observability: The observability of a particular internal circuit node is the degree to which one can observe that node at the outputs of an integrated circuit. Controllability : It is the measure of the ease of setting an internal node to 1 or 0 state via primary inputs. A well designed circuit should have all nodes easily controllable. Fault sampling is one of the approaches to fault analysis. It is used in the circuit where it is impossible to fault every node in the circuit. In this approach, nodes are randomly selected and faulted.

5.

What is a sensitized path?

In D – alg one objective is to propagate a fault at a particular node to one or more primary o/p This path to the o/p pin is called a sensitized path. 6.

What are primary i/p’s and o/p’s?

7.

State the 3 types of fault simulation process.

A primary output(Po) is adirectly observable signal ,such as a pad or a scan o/p .A primary input is one that can be directly set via a pad or some other means. 1. Serial simulation 2. Parallel simulation 3. Concurrent simulation.

8.

What is delay fault testing.

In the case of a high powered NAND gate composed of paralleled n - & p – transistors, if an open ckt occurs as in fig 7.10 pg 483 Weste the gate would still function but with increased pull down time. This is a delay fault. 9. What is ILA testing.

An iterative logic array is a collection of identical logic modules . An ILA is C – testable if it can be tested with a constant number of input vectors independent of the iteration count. An ILA is I testable if a particular fault that occurs in any module as a result of an applied input vector is identical for all modules in an ILA. 10. What are the advantages & disadvantages of IDDQ.

As IDDQ is based on quiescent current measurement which is time consuming, the tests must be run slower than normal ,thus increasing the test time. However this technique gives a form of indirect massive observability at little overhead.

11. What are the various connections of a Test Access Port.(TAP).

The TAP has 4 or 5 single bit connections. They are • TCK(the test clock input) – used to clock tests into & out of chips. • TMS ( The test mode select) – used to control test operations. • TDI ( the test data input) – used to input test data to a chip. • TDO ( test data output) used to output test data from a chip. It also has an optional signal • TRST( The test Reset Signal) used to synchronously reset the TAP controller: also used if a power – up reset signal is not available in the chip being tested.

12. Describe the test architecture of a boundary scan using TAP.

Fig 7.25 pg 502 . Basic test architecture consists of • The TAP interface pins • A set of test data registers to collect datafrom chip • An instruction register to enable test inputs • A TAP controller, which interprets instructions & controls the flow of data. 13. What is a TAP controller.


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The TAP controller is a 16 state FSM that proceeds from state to state based on TCK & TMS signals. It provides signals that control the test data registers & instruction registers. 14.

Explain BYPASS ,EXTEST, SAMPLE /PRELOAD.

The instruction registers has to decode 3 instructions they are. BYPASS – This instruction is represented by an IR having all zeroes in it. It is used to bypass any serial data registers in a chip with a 1 – bit register. This allows specifis chips to be tested in a serial scan scan chain without having to shift through the accumulated SR stages in all the chips. EXTEST – This allows for the testing of off chip circuitry & is represnted by all ones in the IR. SAMPLE /PRELOAD: - This instruction places the boundary scan register in the DR chain and samples or preloads the chip i/os. 15.

What is a test DR.

The test data registers are used to set the inputs of modules to be tested and to collect the results of running tests. 16.

What are boundary scan registers?

The boundary scan register is a special case of a data register. It allows circuit board interconnections to be tested, external components tested, and the state of chip digital I/Os to be sampled.

17. What is the aim of adhoc test techniques?

Reducing the combinational explosion of testing

18. Distinguish functionality test and manufacturing test.

Functionality test is used to confirm the function of a chip as a whole whereas manufacturing tests are used to verify that every gate operates as expected.

19. List the typical manufacturing defects.

Layer to layer shorts ,discontinuous wires,missing or damaged vias, shorts through the thin gate oxide to the substrate or well 20. What is ATPG.

Automatic Test Pattern Generation is a testing tool which can achieve excellent fault coverage 21. What is IDDQ testing.

It is a method of testing for bridging faults PART-B

1. 2. 3. 4. 5. 6.

Explain the different fault models. Explain system level test techniques. (16) (Nov’07) What is self test. Explain how serial scan testing is implemented. Design a block diagram of a test generator for an 8 x 4 K static RAM. What is a programmable logic device? Explain the implementation of a Boolean function using AND OR arrays. Give appropriate diagrams for a suitable example.(16) (Apr ’05) Explain the chip level test techniques. (16) (Nov’07) Explain with diagram the design strategies for testing the CMOS devices.(Nov 08) Explain in detail Scan based test techniques (16) Discuss the 3 main strategies for testability. (16) i) Explain in detail Boundary – Scan test. ii) Enumerate on physical faults with examples. i) Explain Built – in self test. ii) Describe the testing techniques at chip level and at system level. Explain the importance of system level test techniques.

7. 8. 9. 10. 11. 12. 13.

1.

UNIT V: SPECIFICATION USING VERILOG HDL PART -A Write the syntax for switch primitive instantiation.

• •

Syntax: switch_name instance_name(output, data, control_input); Example: nmos n1 (out, data, control);


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pmos p1 (out, data, control); cmos c1 (out, data, ncontrol, pcontrol); List out different data types in verilog.

• Net type: It represents a physical connection between structural elements. Ex: wire • Register type: It represents an abstract data storage element. It is assigned values only within an always statement or an initial statement. Ex: reg 3.

Give the symbol, Truth table and syntax of bufif1.

Truth table:

Input

Syntax: Symbol: 4.

5.

HDL: Hardware Description Language HDL is a standard language to describe the operations of digital circuits.

Name two types of HDLs.

Verilog VHDL: Very High Speed Integrated Circuits Hardware Description Language.

What is module?

• • • • 9.

Structural,Data flow,Behavioral

What is HDL?

• • 8.

Z L H x x

Give the structural coding of an Half adder module HA (a, b, sum, carry) input a, b; output sum, carry; xor (sum, a, b); and (carry, a, b); endmodule What are the types of modeling in verilog?

• • 7.

x L H x x

bufif1 n1 (out, input, control);

• 6.

Control input 0 1 0 z 0 1 z 1 x z x z z x

A module is the description of a unit that performs some function. The basic unit of description in verilog. It describes the functionality or structure of a design. It describes the ports through which it communicates with other modules.

What is the difference between initial and always statement?

• •

Initial statement: It executes only once. Always statement: It executes in a loop i.e. it is executed repeatedly.

10. What is inter-statement delay?

• • •

Inter-statement delay: The delay by which a statement’s execution is delayed. Example: sum = (A^B)^C; #4 carry = A&B + A&C + B&C; The delay in the second statement specifies that the execution of the assignment is to be delayed by 4 time units, and then executes the second assignment.

11. What is intra-statement delay?

• • •

Intra-statement delay: The delay between computing the value of the right-hand side expression and its assignment to the left-hand side. Example: Sum = #3 (A^B)^C; The delay in this statement means that the value of the RHS expression is to be computed first, wait for 3 time units, and then assign the value to the sum

12. List any two capabilities of verilog.


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ISO 9001:2008


DEPARTMENT OF ECE

Primitive logic gates such as AND, OR & NAND are built-in into the language. Flexibility of creating a user-defined primitive (UDP). This UDP can be either combinational or sequential logic primitive.

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13. What are the types of event control?

• Regular event control (edge-triggered ) • Named event control • Event OR control • Level-sensitive timing control 14. What is value set?

Verilog supports four values to model the functionality of real hardware.

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Value levels 0 1 x z

Conditions in hardware circuit Logic 0, false Logic 1, true Unknown value High impedance

15. Define net.

• Net is a data type that represents a physical connection between structural elements. • Its value is determined from the value of its drivers. • The default value to a net is Z. • Nets are declared with the keyword wire. • It can be declared as scalar or vector. 16. Write the syntax for gate primitive instantiation. Gate_name instance_name (out, in_1, in_2, in_3, …….); Example: and g1 (c, a, b); or g2 (c, a, b); 17. Define a port. How is it declared?

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Ports are interface terminals that allow a module to communicate with other modules. These corresponds to the input and output points on a library cell. All ports must be declared within a module lisiting. Unidirectional port can be declared as input in_1, in_2; output out_1, out_2; Bidirectional port can be declared as inout IO_1, IO_2;

18. Define an identifier.

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Identifiers are names of modules, variables, and other objects that can be used in the design. Identifiers consist of upper & lower case letters, digits 0 through 9, the underscore character( _ ) and the dollar sign ($). The first character must be a letter.

19. What is UDP?

User Defined Primitives are self-contained and do not instantiate other modules or primitives. • UDP declaration: primitive UDP_name (port list); 2. Sequential • Two types of UDP: 1. Combinational,

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20. List the types of Gate delay

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The signal propagation delay from any gate input to the gate output can be specified using a gate delay. The gate delay can be specified in the gate instantiation itself. Types of gate delay. rise delay, fall delay, turn-off delay

21. What are the types of structural modeling?


54

ISO 9001:2008


• •

DEPARTMENT OF ECE

Switch instantiation (at the transistor level),Gate instantiation (at the gate level) Module instantiation (to create hierarchy),UDP instantiation (at the gate level)

22. What are the types of procedural assignment? (i) Blocking Procedural assignment:

A procedural assignment in which the assignment operator is an “=” is a blocking procedural assignment. • The assignment statement is executed before the next statement is executed. • Blocking assignment statements are executed in the order they are specified in a sequential block.

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(ii) Non-blocking procedural assignment:

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In a non-blocking procedural assignment, the assignment symbol “<=” is used. It allow scheduling of assignment without blocking execution of the statements that follow in a sequential block.

23. What is the difference between reduction operator & bitwise operator?

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Reduction Operator: It performs a bitwise operation on a single vector operand and yield a 1-bit result. Bitwise Operator: It performs bitwise operation between two vector operands and yield vector result. Example A=4’b1010; B=4’b1101; Z=A&B = 4’b1000 -------------- Bitwise AND operation Z=&A=1’b0 ---------------- Reduction AND operation

24. What is replication operator?

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Replication operator is used to concatenate the same number to the specified number of times. Example: A=4’b1010; Z={ 2 {A}}=8’b1010 1010 In the above example, 2 is the replication constant that specifies how many times to replicate the 4-bit number A inside the bracket. PART-B

1. 2. 3. 4. 5.

Explain the design hierarchies Explain Behavioral RTL modeling. Write notes on priority encoder. Explain how a CMOS D – FLIP –FLOP is constructed . (i) Construct a full adder ckt. And give its verilog HDL coding. (ii) Write the behavioral description for a full adder . 6. (i) List the various data objects in Verilog HDL and explain with examples.(6) (ii)Write the Verilog HDL behavioral and structural description of 4 to 1 MUX (10) 7. Write the Verilog code to simulate a positive edge triggered D FF with synchronous reset i/p: (i) Using IF statement (ii) Using WAIT—UNTIL statement.(16) (APR ‘05) 8. Write the Verilog HDL structural description of full adder and explain (8) (APR ‘05) 9. (i) Give a Verilog structural gate level description of a bit comparator. (10) (ii) Give a brief account of timing control and delay in verilog (6) (Nov’07) 10. (i) Give a Verilog structural gate level description of a ripple carry adder.(10) a. Write a brief note on the conditional statements available in verilog. (6) (Nov’07) 11. a) i) With a neat flow chart explain the VLSI design flow. ii) Explain the syntax of conditional statements in verilog HDL with examples 12. a) i) Explain in detail Behavioural and RTL modeling. ii) Write the program using verilog HDL to implement a Full adder ckt. 13. Explain in detail any 5 operators used in HDL. 14. i) Write the verilog code for 4 bit ripple carry adder.(10) ii) Give the structural description for priority encoder using verilog (6) 15. i) Write a verilog program for 3 to 8 decoder in gate level description(12) ii) What are the differences between behavioural and RTL modeling? (4)


55

ISO 9001:2008

question bank-antenna wave and propogation

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