Malvino Problems
1.
A diode is in series with 220 Ω. If the voltage across the resistor is 4V, what is the current through the
CHAPTER 1|Introduction 1.
A circuit has a Norton current of 10mA and a Norton resistance of 10k Ω. What is the Thevenin circuit?
2.
diode? 2.
Two diodes are in series. The first diode has a voltage of 0.75 V and the second has a voltage of 0.8 V. If the current through first diode is 500 mA, what
A current source has an internal resistance of 1 00k Ω.
is the current through the second diode?
What is the largest load resistance if the current source must appear stiff? 3.
Suppose a current source has an ideal current of 10
CHAPTER 4|Diode Circuits
mA and an internal resistance of 20 M Ω. For what values of load resistance will the current source
1.
A half-wave signal with a peak of 20 V is the input to a choke-input filter. If X L = 5kΩ and X C = 25 Ω, what is
appear stiff?
the approximate peak to peak ripple across the 4.
capacitor?
The internal resistance of a voltage source equals 0.05 ohms. How much voltage is dropped across this internal resistance when the current through it
2.
A center-tapped transformer has a turns ratio of 6:1. What is the rms voltage across the ipper half of the
equals 2A?
secondary winding? The peak voltage? What is the 5.
A flashlight battery has an internal reistance of 1 Ω.
rms voltage across the lower half of the secondary
For what values of load resistance does the flashlight
winding?
battery appear stiff? 3. 6.
If a transformer has a turns ratio of 15:1, what is the
Suppose a voltage source has an ideal voltage of 12
rms secondary voltage? The peak secondary
V and an internal resistance of 0.5 Ωor what values of
voltage? Assume a primary voltage of 120 Vrms.
load resistance will the voltage source appear stiff?
CHAPTER 5|Special purpose diodes 1.
An unloaded zener regulator has a source voltage of 20V, a series resistance of 330 Ω, and a zener voltage
CHAPTER 2|Semiconductors
of 12 V. What is the zener current? 1.
What is the net charge of a copper atom if it gains three electrons?
2.
If the series resistor in (1) has a tolerance of ±10 percent, what is the maximum zener current?
2.
A silicon diode has a saturation current of 10 nA at 25 C. If it operates over a temperature range of 0 to
3.
75 C, what are the minimum and maximum values of
A zener diode has a voltage of 10 V and a current of 20 mA. What is the power dissipation?
saturation current? 4. 3.
4.
A silicon diode has a reverse current of 5µA at 25 C
from 22 to 30 V. If the regulated output voltage is
and 100 µA at 100C. What are the values of the
12V and the load resistance varies from 140 Ω to 10
saturation current and the surface leakage current at
kΩ, what is the maximum a llowable series
25C?
resistance?
A silicon diode has a saturation current of 5 nA at 25 C. What is the saturation current at 100C?
5.
A zener regulator has an input voltage that may vary
If the surface leakage current is 2nA for a reverse
CHAPTER 6|BJTs 1.
A 2N5067 is a power transistor with a base bulk
voltage of 25 V, what is the surface leakage current
resistance r b’ of 10Ω . How much I Brb’ drop is there
for a reverse voltage of 35?
when I B = 1 mA? When I B = 10 mA? When I B = 50 mA?
6.
Assuming a barrier potential of 0.7 V at an ambient temperature of 25C, what is t he barrier potential of
2.
a silicon diode when the junction temperature is
What is the current gain of a transistor with a dc alpha of 0.994?
100C? at 0C? 3.
A transistor has a power power rating of 1 W. If the collector-emitter voltage is 10V and the collector
CHAPTER 3|Diode Theory
current is 120 mA, what happens to the transistor?
4.
If a transistor has a collector current of 100 mA and a
1.
You have two data sheets for amplifiers. The first
collector emitter voltage of 3.5 V, what is its power
shows a cutoff frequency of 1 MHz. The second gives
dissipation?
a risetime of 1 µs. Which amplifier has the greater bandwidth?
5.
A transistor has a current gain of 125 and a base current of 30µA. What is the collector current?
2.
What is the bandwidth of a n amplifier if the risetime is 0.25µs?
6.
A transistor has an emitter current of 10 mA and a collector current of 9.95 mA. What is the base
3.
mW, 4.87 W.
current? 4.
If an ac base current of 50µA produces an ac
If the output power of a preamplifier is 16 dBm, how much power is this in milliwatts?
CHAPTER 9|AC Models 1.
Convert the following powers to dBm: 25 mW, 93.5
5.
The data sheet of an LM380, an audio power amplifier, gives a decibel voltage gain of 34 dB.
collector current of 7.5mA, what is the ac beta?
Convert this to ordinary voltage gain. 2.
If the ac collector current is 4 mA and the ac beta is 300, what is the ac base current?
6.
A dc amplifier has a midband voltage gain of 100. If the upper cutoff frequency is 10 kHz, what is the voltage gain for each of these input frequencies: 100 kHz, 200 kHz, 500 kHz, and 1 MHz?
CHAPTER 11|POWER AMPLIFIERS 1.
An amplifier has an input power of 4 mW and output
7.
An amplifier has a midband voltage gain of 1000. If cutoff frequencies are f 1 = 100 Hz, and f 2 = 100 kHz,
power of 2 W. What is the power gain?
what does the frequency response look like? What is the voltage gain if the input frequency is 20 Hz? If it CHAPTER 13|JFETs 1.
is 300 kHz?
A 2N4416 has I DSS = 10 mA and g m0 = 4000 µS. What is its gate-source cut off voltage? What is the value of gm0 for VGS = -2V?
2.
A 2N5670 has I DSS = 12 mA and V GS(OFF) = -3 V. What
CHAPTER 17|Differential Amplifiers 1.
90 dB. What is the common-mode voltage gain? If
are the gate voltage and drain current at the half
the desired and common-mode signal each has a
cutoff point? 3.
A 741 is an op amp with A = 200,000 and CMRR dB =
value of 1 µV, what is the output voltage?
A 2N5457 has I DSS = 1 to 5 mA and V GS(OFF) = -0.5 to -6 V. What are the minimum and maximum values of RDS?
4.
A JFET has I DSS = 16 mA and V p = 3 V. What is the
CHAPTER 18|Operational Amplifiers 1.
value when the load resistance is 500 Ω? The open
maximum drain current? The gate-source cutoff
loop voltage gain at 1 kHz?
voltage? The value of R DS? 5.
A 2N5458 has a gate current of 1 nA when the
2.
happens to the initial slope if the frequency
of the gate? A JFET shunt switch has R D = 10 k Ω, IDSS = 10 mA, and VGS(OFF) = -2 V. If vin = 10 mV pp, what are the output
increases to 30 kHz? 3.
An LM675 has a slew rate of 8V/µs. What is the power bandwidth for a peak output voltage of 5V?
voltages? What is the on-off ratio? 4. CHAPTER 14|MOSFETs
What is the initial slope of a sine wave with a frequency of 15 kHz and a peak value of 2 V? What
reverse voltage is -20V. What is the input resistance
6.
What is the CMRR of a 741C at 100 kHz? The MPP
What is the open loop voltage gain of an LF157A when the input frequency is 1 kHz? 10 kHz? 100 kHz? (Assume a first order response, that is, 20 dB per
1.
An E-MOSFET has these values: I D(active) = 1 mA and
decade rolloff.)
VDS(active) = 10 V. What does its drain resistance equal in the active region? CHAPTER 19|Negative Feedback CHAPTER 16|Frequency Effects
1.
A VCVS amplifier uses an LM741C with f unity = 1 MHz
6.
and SR = 0.5 V/µs. If ACL = 5, what is the closed loop
An astable 555 timer has R 1= 10 k Ω, R2 = 2kΩ, and C = 0.0047 µF. What is the frequency?
bandwidth? The largest undistorted peak output voltage at f 2(CL)? 2.
An ICVS amplifier uses an OP-42E with A OL = 500,000 and f 2(OL) = 20 Hz. What is the closed loop
CHAPTER 24|Regulated Power Supplies 1.
bandwidth? 3.
A VCVS amplifier uses an LM324 with (1 + A OLB) =
In a buck regulator LT1074, R 1 = 2.21 k Ω and R2 = 2.8 kΩ. What is the output voltage?
2.
2000 and f 2(OL) = 2 Hz. What is the closed loop
In the buck boost regulator MAX631, R 1 = 1kΩ and R 2 = 5.79 k Ω, what is the output voltage?
bandwidth? 3.
The LM7805 can regulate specifications with an input voltage between 7.5 and 20 V. What is the maximum efficiency? What is the minimum
CHAPTER 21|Active Filters
efficiency? 1.
A bandpass filter has lower and upper cutoff frequencies of 445 and 7800 Hz, respectively. What
2.
and the minimum load resistance is 10 Ω, it has a
wideband or narrowband filter?
load regulation of ________.
Identify the following filters as narrowband or
VHL = 11.2 V for line voltage 125 V rms
If a Butterworth filter contains 10 capacitors, what is
A bandpass filter has a center frequency of 50 kHz
You are testing a butterworth filter with the kHz. What is the a ttenuation at each of the following frequencies? 4, 8 and 20 kHz? A Chebyshev Sallen-Key unity-gain low-pass filter has a cutoff frequency of 7.5 kHz. The ripple depth is 12 dB. If n = 2 and R = 25 k Ω, what do C 1 and C2 equal?
CHAPTER 23|Oscillators 1.
Draw the block diagram of a PLL.
2.
A crystal has these values: L = 3 H, C S = 0.05 pF, R = 2kΩ, and C m = 10 pF. What are the series and parallel resonant frequencies of the crystal?
3.
An Armstrong oscillator has M = 0.1 µH and L = 2µH. What is the feedback fraction? What is the minimum voltage gain needed to start the oscillations?
4.
A crystal has a thickness of t. If you reduce t by 1 percent, what happens to the frequency?
5.
values:
and f 2 = 160 Hz
following specifications: n = 10, A p = 3 dB, and f C = 2
6.
Suppose that a power supply has these measured VLL = 9.2 V for line voltage 105 V rms
and a Q of 20. What are the cutoff frequencies? 5.
5.
and f 2 = 75 kHz; c) f 1 = 2 Hz and f 2 = 5 Hz; d) f 1 = 80 Hz
its roll-off rate? 4.
If a power supply has an output resistance of 1.5 Ω
are the bandwidth, center frequency, and Q? Is this a
wideband: a) f 1 = 2.3 KHz, f 2 = 4.5 kHz; b) f 1 = 47 kHz
3.
4.
A 555 timer is connected for monostable operation. IF R = 10 k Ω anc C = 0.022 µF, what is the width of the output pulse?
What is the line regulation?
