VLSI Lab Compendium

VLSI Design – EEE 434 Lab Compendium

Student Name: _________________________ ___________________________ __ Registration No: ___________________________ Semester: ___________________________ Date: ___________________________

_______________________________________________ Date and signature of student:

_______________________________________________ Date and signature of lab instructor:

Shahzad Asif February, 2009

Department of Electrical Engineering COMSATS Institute of Information Technology


List of Lab Lab Experiments Experiments

DESCRIPTION OF LAB

PAGE NO.

Lab 1

MOSFET Characteristics using DSCH

2

Lab 2

Inverter Characteristics using DSCH

8

Lab 3

Basic Gates Implementation in DSCH and Microwind

11

Lab 4

Combination Combinational al Logic Logic (Full Adder) Implementa Implementation tion in DSCH DSCH and Microwind Microwind

14

Lab 5

CMOS Inverter(Layout Design) Implementation in DSCH and Microwind

16

Lab 6

AND Gate (Layout Design) Implementation in DSCH and Microwind

Lab 7

30

Lab 8

Transistor Sizing for Large Capacitive Loads Implementation in DSCH and Microwind Pass Transistor Logic Implementation in DSCH and Microwind

Lab 9

Manchester Carry Chain Adder Implementation in DSCH and Microwind

35

Lab 10

Carry Save Multiplier Implementation in DSCH and Microwind

37

Lab 11

Barrel Shifter Implementation in DSCH and Microwind

39

Lab 12

NAND ROM and NOR ROM Implementation in DSCH and Microwind

41

Lab 13

SRAM Implementation in DSCH and Microwind

43

Lab 14

DRAM Implementation in DSCH and Microwind

45

VLSI Design – EEE 434

22

32

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Lab # 01: MOSFET Characteristics 1. Objective

In this lab, you will study the behaviour of NMOS and PMOS the tools which will be used for the labs are DSCH2 and Microwind. 2. Theory 2.1. MOSFET The metal-oxide-semiconductor field effect transistor is very important part of the digital design. It is mostly used as a switch. MOSFET is a four terminal device. The voltage applied to the gate determines the amount of current flows between s ource and drain ports. The body of the transistor (BULK) represents the fourth terminal.

Note: Mostly the fourth terminal (bulk/body) of a MOS is connected to a DC supply that is identical for all devices of the same type (GND for NMOS, VDD for PMOS), so this terminal is not shown on the schematics. 2.2 NMOS

The NMOS transistor consists of n+ drain and n+ n + source regions which are embedded in a p-type substrate. The current is carried by electrons moving through an ntype channel between source and drain. 2.3 PMOS

The PMOS transistor consists of p+ drain and p+ source regions which are embedded in an n-type substrate. The current is carried by electrons moving through an ntype channel between source and drain. 2.4 CMOS

The CMOS (Complementary MOS) MOS) consists of both p-type p -type and n-type MOS. The advantage of CMOS is its low power design. 3. Design

For this lab we have selected a simple NMOS based design for experimentation.


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Figure 1. Test Circuit for NMOS 4. Lab Instructions 4.1. Schematic Design (DSCH)

1. 2. 3. 4.

Open DSCH. Select the CMOS 025 foundry by selecting File  Select Foundry Save the design frequently, during the elapse of the lab session. Drag the required components from the symbol library. The symbol library can be opened from View  Symbol Library 5. Connect the components as shown in figure 1. 6. Check if there are any floating lines. Simulated  Check Floating Lines. 7. Simulate the design. Simulate  Simulation. 8. Carefully observe the results and fill table 1 given below. 9. The timing diagram can be viewed by selecting View  Timing Diagrams. 10. To 10. To create a Verilog file, select File  Make Verilog File. 11. A 11. A window will appear as shown below, uncheck all the check boxes and click on OK.


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Figure 2 SR# 1 2 3 4

Input at Gate 0 0 1 1

Input at drain 0 1 0 1 Table 1

Output

4.2. Layout Editor (Microwind)

To see the layout of this design follow the following steps. 1. 2. 3. 4.

Open Microwind. Select the cmos025 foundry by selecting File  Select Foundry. Select Compile  Compile Verilog File. Select the file generated by DSCH2. A window will be opened as shown below.


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Figure 3. 5. 6. 7. 8. 9.

Click on the ‘Compile’ button. Click on the ‘Back to Editor’ button, the layout will be generated. Save your design. To check if there are any errors, select Analysis  Design Rule Checker To see the simulation results, select Simulate  Run Simulation.

The characteristics of PMOS are similar to the NMOS. Design the test circuits for PMOS and Study its behaviour. 5. Simulation

Max Time Delay for NMOS: ________________ Max Time Delay for PMOS: ________________ Dimension of the Layout for NMOS (in Lambda): ________________ Dimension of the Layout for PMOS (in Lambda): ________________ 6. Results

Explain the functionality of the designed NMOS ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________


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Explain the functionality of the designed PMOS ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ Draw the circuit designed for PMOS

Find out the maximum drain current when Vd is varied through 0 values of Vg given in the table.

2.5V, for the

Note: Use low-leakage NMOS device to fill the table.


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Table 2. What is the affect of W/L on IDs? Explain the affect of Vb to the threshold voltage for NMOS devices. Explain the affect of Vb to the threshold voltage for PMOS devices. Explain the affect of Vb to Ids for NMOS devices. Explain the affect of Vb to Ids for NMOS devices. What is the affect of Vg to Cgs (gate to source capacitance). What is the affect of Vg to Cgd (gate to drain capacitance). What is the affect of temperature on the following? 1. 2. 3.

Capacitance Threshold Voltage Drain Current (IDs)


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Lab # 02: Inverter Characteristics 1. Objective In this lab, students will design a CMOS inverter and study its behavior. The observation includes input to output delay, affect of transistor size on delay, gain, etc. Note: Make sure that you are familiar with DSCH2 and Microwind, and you have no problem in using the options of these tools. Study the lab manual before coming to the lab to have a better understanding of the problem.

2. Design

Figure 1. Test Circuit for Inverter.

3. Lab Instructions 3.1. Schematic Design (DSCH2) 1. 2. 3. 4. 5. 6. 7.

Open DSCH2. Select the cmos025 foundry by selecting FileSelect Foundry. Save the design frequently, during the elapse of the lab session. Draw the circuit shown in Figure 1. Check for floating lines, and if needed remove them. Simulate the design and observe the results. Create a Verilog file of the design.

3.2. Layout Editor (Microwind) To see the layout of this design follow the following steps. 1. Open Microwind. 2. Select the cmos025 foundry by selecting FileSelect Foundry. VLSI Design – EEE 434

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Department of Electrical Engineering COMSATS Institute of Information Technology 3. Select CompileCompile Verilog File. 4. Select the file that you have generated by DSCH2 and compile it. 5. Save the Layout.

4. Simulation (Microwind) and Results 1. Select SimulateRun SimulationStatic Voltage vs. Voltage. The following window will appear.

2. Check the ‘X(50%)’ checkbox and click on reset button. Note the value of Vc in the table 1. 3. You can change the simulation parameters by selecting simulateSimulation Parameters. Fill the table 1 for different values of Vdd. Repeat the same experiment with different length of NMOS & PMOS, and fill table 2 for the default simulation parameters. Sr. # Vdd Supply (in Volts) Vc at y = Vdd/2 1 2 3 4 5 Table 1. VLSI Design – EEE 434

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Sr. #

Width of NMOS

Width of PMOS

Input to Output Delay

Vc at y = Vdd/2

1 2 Table 2. When we use NMOS and PMOS transistors of same size, the time that it takes to change the output from 0 to 1 is more than the time for 1 to 0. The reason for this is that the mobility of electrons is more than the mobility of holes. To solve this problem we use PMOS with larger width than NMOS. Keeping the length of transistors constant fill the table 3 for different values of widths for which the inverter becomes symmetric. Sr. # 1 2 3

Width of NMOS

Width of PMOS

0

1 time

1

0 time

Table 3 Explain the affect on Input to Output delay due to different size of transistors. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ Explain the affect of different size of transistors on the voltage curve of output. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ Explain the relationship of Vdd and output curve. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________


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Lab # 03: Basic Gates 1. Objective This lab consists of basic gates design. Students will design AND, XOR & XNOR gates at transistor level and observe their behavior. Note: Make sure that you are familiar with DSCH2 and Microwind, and you have no problem in using the options of these tools. Study the lab manual before coming to the lab to have a better understanding of the problem.

2. Theory 2.1. Complementary MOS A static CMOS gate is a combination of two networks, the pull-up network (PUN) and the pull-down network (PDN). The function of the PUN is to provide a connection between the output and Vdd anytime the output of the logic gate is meant to be 1. Similarly, the function of PDN is to connec t the output to Vss when the output of the logic gate is meant to be 0. At a particular time, only one of these networks conducts.

2.2. Construction of CMOS •

•

•

•

•

The PDN is constructed using NMOS devices because they produce “strong zeros”, while the PUN is constructed using PMOS devices due to their capability of producing “strong ones”. NMOS devices connected in series correspond to an AND function. Similarly, NMOS connected in parallel represent an OR function. In contrast, PMOS transistors connected in series conducts if both inputs are low which represent a NOR function. PMOS connected in parallel implement a NAND function. PUN and PDN of a CMOS structure are dual ne tworks. This means that a parallel connection of transistors in the PUN corresponds to a series connection of transistors in the PDN. To construct a CMOS, only on e network is designed and the other network is obtained using the duality principle. The complementary gates such as NOR, NAND, XNOR can be designed in a single stage, while the gates such as AND, OR, XOR require an additional inverter to complete the design. The number of transistors required to implement an N-input logic ga te is 2N.

Complementary CMOS is explained in the book (Digital Integrated Circuits by Jan M. Rabaey) on page 236-240.


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3. Design of AND Gate As it is mentioned that the AND can be obtained by connecting the NMOS devices in series. And by complementing it we get the PMOS devices in parallel. As AND gate is not a complementary gate so we need to place an inverter at second stage to complete the required circuit.

Figure 1. Test Circuit for AND gate

3. Lab Instructions 3.1. Schematic Design (DSCH2) 8. Open DSCH2. 9. Select the cmos025 foundry by selecting FileSelect Foundry. 10. Save the design frequently, during the elapse of the lab session. 11. Draw the circuit shown in Figure 1. 12. Check for floating lines, and if needed remove them. 13. Simulate the design and observe the results. 14. Create a Verilog file of the design.

3.2. Layout Editor (Microwind) To see the layout of this design follow the following steps. 6. Open Microwind. 7. Select the cmos025 foundry by selecting FileSelect Foundry. 8. Select CompileCompile Verilog File. 9. Select the file that you have generated by DSCH2 and compile it. 10. Save the Layout.


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Design the circuits for XOR & XNOR in DSCH2 and fill the tables 1 & 2 respectively.

Sr. # 1 2 3 4

A 0 0 1 1

B 0 1 0 1

Out

Table 1. XOR Gate Results

Sr. # 1 2 3 4

A 0 0 1 1

B 0 1 0 1

Out

Table 2. XNOR Gate Results

Draw the circuits designed for XOR & XNOR ga tes.


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Lab # 04: Combinational Logic (Full Adder) 1. Objective

In this lab, students will implement a 1-bit full adder at transistor level. The software used will be DSCH. Note: Make sure that you are familiar with DSCH2 and Microwind, and you have no problem in using the options of these tools. Study the lab manual before coming to the lab to have a better understanding of the problem.

2. Theory 2.1. Full Adder A 1-bit full adder has 3 inputs and two outputs. 2 inputs are the numbers which are to be added and one input is the carry in. The outputs are sum and carry out.

A

Sum Full Adder

B

Cout

Cin Figure 1. Block Diagram of Full Adder

2.2. Truth Table for Full Adder

A 0 0 0 0 1 1 1 1

B 0 0 1 1 0 0 1 1

Cin 0 1 0 1 0 1 0 1

Sum 0 1 1 0 1 0 0 1

Cout 0 0 0 1 0 1 1 1

Figure 2. Truth Table for Full Adder


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2.3. Logic Equations for Cout The equation for Cout obtained from the truth table in figure 2 is Cout = ABC` + A`BC + AB`C + ABC By simplifying this equation, we get Cout = AB + AC + BC ……………. (1) Cout = A (B+C) + BC ……………… (2)

3. Lab Instructions

Design the circuit for Cout according to equations (1) & (2), and find out the difference in the design and results. Write the equation for sum and complete the full adder circuit. 4. Results and Observations 1) Number of transistors used for Cout using equation (1) _____________________________ 2) Number of transistors used for Cout using equation (2) _____________________________ 3) Input to Output delay for Cout using equation (1) _____________________________ 4) Input to Output delay for Cout using equation (2) _____________________________ 5) Equation for the sum _____________________________ 6) Number of transistors used for Sum _____________________________ 7) Input to Output delay for Sum _____________________________ 8) Attach the circuit diagram for complete circuit (optimized for area and speed).


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Lab # 05: CMOS Inverter(Layout Design) 1. Objective

In this lab students will start working with layouts. Students will draw the layout of single NMOS & PMOS transistors, and finally a CMOS inverter will be designed. Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Theory 2.1. Lambda-based design rules In general, design rules and layout methodology based on the concept of λ provide a process and feature size-independent way of setting out mask dimensions to scale. All paths in all layers will be dimensioned in λ units and λ can be assigned any appropriate value which is compatible with the fabrication process. This means that we do not need to remember the design rules for different technologies but a single set of rules is used for all technologies. For example, the minimum width of poly silicon can be 2λ . We can find out the actual value for different technologies by simply putting the value of λ For 0.25u technology, 2λ = 0.5um For 0.12u technology, 2λ = 0.24um Lambda-based design rules are explained in the book (Basic VLSI Design by Douglas A. Pucknell) on page 73.

2.2. Lambda-based and micron-based design rules For the lambda-based design rules, the rules are formulated in terms of a length unit of λ which is related to the resolution of the process. Lambda may be viewed as a bound on the width deviation of a feature from its idea size and also as a bound on the maximum misalignment of any one mask. A con sequence of using the lambda-based rules is that every dimension must be rounded up to whole λ values and this leads to layouts which do not fully exploit the capabilities of the process. On the other hand, micron-based rule sets utilize the full advantages of the fabrication line capabilities and tighter layouts result. Suppose for example, that the micron-based rules a llow the minimum poly silicon width to be of 0.48um when using 0.25 process. If we derive lambda-based design rules


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Department of Electrical Engineering COMSATS Institute of Information Technology for this then λ for 0.25 process will be 1.92. As λ is an integer value so the rounded value for λ is 2. More information can be found in the book (Basic VLSI Design by Douglas A. Pucknell) on page 79.

2.3. Architectural Issues In all design processes, a logical and systematic approach is essential. Some guidelines can be set out as follows: 1. 2. 3. 4. 5. 6. 7.

•

•

Define the requirements (properly and carefully). Partition the overall architecture into appropriate subsystems. Draw a floor plan of how the system is to map onto the silicon. Aim for regular structures so that design is largely a matter of replication. Convert each cell to layout. Carefully and thoroughly carry out a design rule check on each cell. Simulate the performance of each cell/subsystem. The whole design process will be greatly assisted if considerable care is taken with: The partitioning of the system so that there are clean and clear subsystems with a minimum interdependence and complexity of interconnection between them. The design simplification within subsystems so that architectures are adopted which allow the exploitation of a cellular design concept. This allows the system to be composed of relatively few standard cells which are replicated to form highly regular structures. Architectural Issues are explained in the book (Basic VLSI Design by Douglas A. Pucknell) on page 147.

3. Lab Instructions Use 0.25 design rule file for the CMOS inverter design.

3.1. MOS Generator For the layout of NMOS and PMOS we will use the MOS Gen erator tool. It is the first button of the second row in the palette. Clicking on this button will display the window shown in figure 1.


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Figure 1. MOS Generator Tool Select the device type (PMOS or NMOS). Set the number of figures to g enerate and then click on the ‘Generate Device’ button. Click on the window and the device will be placed there.

3.2. Creating a CMOS Inverter To create a CMOS Inverter, follow the following steps. 1. Draw layout for NMOS using the ‘MOS Generator’. 2. Draw layout for PMOS using the ‘MOS Generator’ and place it ab ove NMOS as shown in figure 2.

Figure 2. NMOS and PMOS VLSI Design – EEE 434

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3. Connect the gates (poly silicon) and drains (metals) of the two devices as shown in figure 3.

Figure 3. Connecting gates and drains 4. Connect the Vdd supply (first button on third row) to the source of PMOS. 5. Connect the Ground (third button on third row) to the source of NMOS. 6. Click on the ‘Design Rule Checker’ and correct the errors if any. The layout of CMOS Inverter is completed.

3.3. Adding Input and Output To simulate the design, you need to add input and output to the device. The steps are given below: 1. Click on ‘Add a Clock’ (fourth button on third row) and then click on the poly silicon (gate). A window will appear as shown in figure 4.


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Figure 4. Adding a Clock to input

2. Set the properties of clock according to figure 4 and then click on ‘Assign’ button. 3. Click on the ‘Visible Node’ (last button on third row) and then click on the drain of MOS. Then click on ‘Assign’ button in the window displayed. 4. Click on the ‘Add Virtual Capacitance’ (third button on second row) and then click on the output of the inverter. Set the desired value of capacitance and click on ‘Assign’ button.

4. Simulation and Results 4.1 Simulating the Design To simulate the design, click on the ‘Run Simulation’ button. An error window will be displayed indicating that the N-Well region is floating. The reason of this error is that the N-Well is neither connected to Ground nor with Vdd supply. To remove this error, connect the N-Well with Vdd Supply. Final design of inve rter is shown in figure 5. Again run the simulation and there should be no errors. Run the simulation for different values of capacitance and fill the table 1.


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Figure 5. Final design of the inverter

Sr. No 1 2 3 4 5 6 7 8 9 10

Virtual Capacitance Value 0.0001 pf 0.001 pf 0.010 pf 0.050 pf 0.100 pf 0.500 pf 1.000 pf 2.000 pf 5.000 pf 10.00 pf

0

1 Time

1

0 Time

Table 1. Effect of Load capacitance on Transition Times


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Lab # 06: AND Gate (Layout Design) 1. Objective

In this lab, a CMOS AND gate will be implemented at layout level. Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Theory 2.1. Schematic Design

Figure 1. Schematic of AND Gate

There are 2 NMOS and 2 PMOS in the design excluding inverter. NMOS are in series while PMOS are in parallel. The important thing to note is that NMOS are connected such that the drain of one is connected to the source of other, and there is not any other connection at their joining. But in PMOS both the source and the drains are connected with each other and every terminal of the PMOS transistor is connected to some other wire in the circuit. This thing will result in a complex layout for PMOS as compared to NMOS. We can draw the same circuit as in the figure 2 or in figure 3 for having a different view of the circuit. The implementation of circuit given in figure 3 can be understood more easily so we will consider this circuit for our layout design.


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3. Lab Instructions Use 0.25 design rule file for the CMOS inverter design.

3.2. Creating a CMOS AND Gate To create a CMOS AND gate, follow the following steps. 7. Draw layout for NMOS using the ‘MOS Generator’, this time set the number of figures to 2. 8. Draw layout for PMOS using the ‘MOS Generator’ and place it ab ove NMOS as shown in figure 4.

Figure 4. NMOS and PMOS


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9. Connect the gates (poly silicon) of PMOS and NMOS. As there is no connection at the junction of two NMOS transistors so we can remove this metal as shown in figure 5.

Figure 5. Connecting Gates and removing extra metal 10. Connect the drains of PMOS with each other and then the drain of NMOS as shown in figure 6.


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Figure 6. Connecting the drains of PMOS and NMOS 11. Place an inverter layout next to this design as shown in figure 7.

Figure 7. Placing an inverter layout VLSI Design – EEE 434

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Department of Electrical Engineering COMSATS Institute of Information Technology 12. Connect the drain of first layout to the gate of the inverter as shown in figure 8.

Figure 8. Connecting drain of first layout with the inverter gate 13. Connect the source of NMOS with each other and connect them to Ground. 14. Connect the source of PMOS with each other and connect them to Vdd as shown in figure 9.


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Figure 9. The layout of CMOS AND gate is complete.

3.3. Adding Input and Output To simulate the design, you need to add input and output to the device. The steps are given below: 5. Connect the inputs (two poly gates) with the metal 2 and then with metal 3 so that they come outside of the layout. Then do same with the output as shown in figure 10. 6. Assign the inputs and outputs as shown in the figure 10.


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Figure 10. Final Design of AND gate

4. Simulation and Results Run the simulation and answer the following questions. 1) What is maximum output load capacitance that this gate can drive without affecting the transition times? ________________________________________________________ 2) What is the maximum output load capacitance where the transition times have no significant affect? ________________________________________________________ 3) What is the maximum output load capacitance where this gate can still operate correctly? ________________________________________________________ 4) What is the minimum output load capacitance where t his gate has no affect on output? ________________________________________________________


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Lab # 07: Transistor Sizing for Large Capacitive Loads 1. Objective

In this lab, a chain of inverters will be designed to drive a large output load capacitance (10pF). Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Theory 2.1. Large Output Capacitance Most of the time, the output of a transistor is connected to inputs of only a small number of transistors, so we do not need to worry for the load capacitance. But if the output of a transistor is connected to a device having high input capacitance or a large number of devices are attached to the output of the transistor, then the transistor with minimum width is unable to drive these devices. To solve this problem, we need to increase the width of the transistor but this will degrade the T phl and T plh. To balance these two problems we need to use the transistor in series where each transistor is bigger than the previous transistor and smaller than the next transistor.

2.2. Sizing Inverters for the specified Load Capacitance The input capacitance of the inverter is 2.5fF. We are required to drive a load capacitance of 10pF. For this, we will have to decide the number of inverters in the chain and their sizes. We will use 2/1 ratio for the first inverter width and then use the formulae to decide the other inverter sizes. The number of stages can be found by the following formula Nopt = ln(load capacitance/input capacitance) Scaling factor for each inverter can be found by the following formula A = (load capacitance/input capacitance)

1/N

3. Homework You must complete the following tasks before coming to lab to save the time. 1. Find the optimal number of stages of inverter ‘Nopt’. 2. Find the Scaling Factor ‘A’ for the problem. 3. Find the total delay of the design. VLSI Design – EEE 434

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4. Lab Instructions 1. Use 0.25 design rule file for the layout design. 2. Design each inverter separately and test each of them before combining with the other inverters. 3. Combine inverters one by one, and after adding each inverter simulate the design carefully. 4. Add the specified load capacitance, and check the timings of the design.

5. Simulation and Results Input Capacitance: _______________________ Load Capacitance: _______________________ Number of stages Nopt: _______________________ Scaling Factor A: _______________________ Calculated Tphl: ________________________ Observed Tphl: ________________________ Calculated Tplh: ________________________ Observed Tplh: ________________________


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Lab # 08: Pass Transistor Logic 1. Objective

In this lab, students will draw layout for the NAND gate with two different methods and compare the two designs. Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Theory 2.1. Pass Transistor Logic Pass-Transistor logic is widely used to reduce the number of transistors required to implement logic. In this technique the source-drains terminals of transistors can be drive by the inputs. The design consists of NMOS transistors but for inverter fully CMOS design is used. As NMOS passes a strong ‘0’ and a weak ‘1’, so in case of a ‘1’ the output only charges up to Vdd – VTn. Due to this reason, pass-transistor gates cannot be cascaded by connecting the output of a pass gate to the gate input of another passtransistor. Similar to CMOS, the voltage transfer curve (VTC) of pass-transistor logic is data dependent. A pure pass-transistor gate is not regenerative. Slow signal degradation will be observed after passing through a number of subsequent stages. This can be cater by the occasional insertion of a CMOS inverter.

2.2. Schematics of NAND gate

Figure 1. NAND Gate (schematic 1) VLSI Design – EEE 434

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Figure 2. NAND Gate (schematic 2)

3. Lab Instructions 5. Use 0.25 design rule file for the layout design. 6. The two designs are quite similar so you will not need to draw each transistor separately. 7. Do not forget to save the design during the work.

4. Simulation and Results T plh for design 1: _____________________________ T phl for design 1: _____________________________ T plh for design 2: _____________________________ T phl for design 2: _____________________________ Number of Transistors in design 1: ______________ Number of Transistors in design 2: ______________


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Comparison of Design 1 & Design 2 Sr. #

Design 1

Design 2

1 2 3 4 5 6

Briefly Explain which design should be used and Why?

_____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________


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Lab # 09: Manchester Carry Chain Adder Implementation 1. Objective

In this lab, students will implement a 4 bit Manchest er Carry Chain Adder in DSCHV and Microwind. Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Schematics

V DD

P 0

P 1

P 2

P 3 C 3

C i ,0

G 1

G 0

C 0

G 3

G 2

C 1

C 2

C 3

Figure 1. Manchester Carry Chain

3. Lab Instructions 8. Use 0.25 design rule file for the layout design. 9. Do not forget to save the design during the work.


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4. Simulation and Results T plh for design: _____________________________ T phl for design: _____________________________ Number of Transistors in design: ______________ Total Delay ‘Cout’: ______________ Latency: ______________

5. Draw complete 4-bit adder circuits.


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Lab # 10: Carry Save Multiplier Implementation 1. Objective

In this lab, students will implement a 4 bit Carry Save Multiplier Implementation in DSCHV and Microwind. Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Schematics

HA

HA

HA

HA

HA

FA

FA

FA

HA

FA

FA

FA

FA

FA

HA

HA

Vector Merging Adder

Figure 1. Carry Save Multiplier



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4. Simulation and Results T plh for design: _____________________________ T phl for design: _____________________________ Number of Transistors in design: ______________ Latency: ______________

5. Draw complete 4-bit multiplier circuits.


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Lab # 11: Barrel Shifter Implementation 1. Objective

In this lab, students will implement a 4 bit Barrel Shifter Implementation in DSCHV and Microwind. Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Schematics

A3

B3

Sh1 A2 B2

Sh2

: Data Wire

A1 B1

: Control Wire

Sh3 A0 B0

Sh0

Sh1

Sh2

Sh3

Figure 1. Barrel Shifter

3. Lab Instructions 12. Use 0.25 design rule file for the layout design. 13. Do not forget to save the design during the work. VLSI Design – EEE 434

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5. Draw complete 4-bit Shifter circuits.


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Lab # 12: Nand ROM and NOR ROM Implementation 1. Objective

In this lab, students will implement a 4 bit NAND ROM AND NOR ROM Implementation in DSCHV and Microwind. Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Schematics V DD

V D

Pull-up devices

Pull-up devices BL [0]

BL [1]

BL [2]

BL [3]

WL [0] WL [0] GND WL [1] WL [1] WL [2] WL [2] GND WL [3]

WL [3]

BL [0]

BL [1]

BL [2]

BL [3]

Figure 1. NOR ROM AND NAND ROM EXAMPLES

3. Lab Instructions 14. Use 0.25 design rule file for the layout design. 15. Do not forget to save the design during the work. 16. You have to store the following data’s: 0110,1000,0111,1001.

4. Simulation and Results T plh for design1: _____________________________ T phl for design1: _____________________________ Number of Transistors in design1: ______________


Page 41 of 46

Department of Electrical Engineering COMSATS Institute of Information Technology Latency1: ______________ T plh for design2: _____________________________ T phl for design2: _____________________________ Number of Transistors in design2: ______________ Latency2: ______________

5. Draw complete circuit diagrams.


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Lab # 13: SRAM Cell Implementation 1. Objective

In this lab, students will implement a SRAM CELL in Microwind. Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Schematics

W D 2

4

Q 5

Q

6

1

3

B

B

Figure 1. SRAM CELL



Page 43 of 46




Page 44 of 46


Lab # 14: DRAM Cell Implementation 1. Objective

In this lab, students will implement a DRAM CELL in Microwind. Note: Make sure that you are familiar with Microwind. Study the lab manual before coming to the lab to have a better understanding of the problem. You must have a copy of the design rules while working in the lab.

2. Schematics

B

B

1

2

WW WWL

RW

3

M 1

RWL

V DD 2 V T

X

2

C S

BL

1

BL

2

V DD

V DD 2 V T

DV

Figure 1. DRAM CELL


4. Simulation and Results T plh for design: _____________________________ T phl for design: _____________________________ Latency: ______________


Page 45 of 46

MICROWIND & DSCH USER'S MANUAL

11. Design Rules

11 Design Rules 11.1 Select a Design Rule File The software can handle various technologies. The process parameters are stored in files with the appendix '.RUL'. The default technology corresponds to a generic 6-metal 0.25µm CMOS process. The default file is CMOS025.RUL. To select a new foundry, click on File -> Select Foundry and choose the appropriate

-

technology in the list. -

To set a specific foundry as the default foundry, click Files -> Properties , 'Set as Default Technology'.

11.2 Start Microwind with a specific design Rule File To start Microwind with a specific design rule file, click with the right button of the mouse on the Microwind icon, select the "Properties" item, then the target. The default target may be: C:\microwind2\Microwind2.exe

The command line may include two more parameters: -

The First parameter is the default mask file loaded at initialization

-

The Second parameter is the design rule file loaded at initialization

The following command executes MICROWIND2 with a default mask file « test.MSK » and the rule file « cmos018.RUL ». C:\microwind2\Microwind2.exe test cmos018.rul

11.3 Nwell Design Rules r101

Minimum well size : 12 λ

r102

Between wells : 12 λ

r110

Minimum surface : 144 λ

2

r 101

r 102

nw ell

nw ell p substrate

92

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11. Design Rules

11.4 Diffusion Design Rules r201

Minimum N+ and P+ diffusion width : 4 λ

r202

Between two P+ and N+ diffusions : 4 λ

r203

Extra nwell after P+ diffusion : 6 λ

Nwell polarization

r203

r204 Between N+ diffusion and nwell : 6 λ

P+ diff

r205 Border of well after N+ polarization 2 λ r206 Distance between Nwell and P+ polarization 6 λ r210

r202

N+

r205

P+ diff

r201

nwell

2


r204

r206

N+ diff

P+

P+ olarization

11.5 Polysilicon Design Rules r301

Polysilicon width : 2 λ

r302

Polysilicon gate on diffusion: 2 λ

r303

Polysilicon gate on diffusion for high

r305

voltage MOS: 4 λ

P+dif

r304

Between two polysilicon boxes : 3 λ

r305

Polysilicon vs. other diffusion : 2 λ

r306

Diffusion after polysilicon : 4 λ

r307

Extra gate after polysilicium : 3 λ

r310


r302

r301

r306

r304

2

r303 r306 N+dif r307 High voltage MOS

93

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11. Design Rules

r305

P+diff r306

r302

nwell

r304

r301

r306 N+diff

r307

11.6 2nd Polysilicon Design Rules r311

Polysilicon2 width : 2 λ

r312

Polysilicon2 gate on diffusion: 2 λ

r311

Pol 2

r312

11.7 Option Design Rules rOpt

Border of “option” layer over diff N+ and diff P+

rO N+dif

11.8 Contact Design Rules r401

Contact width : 2 λ

r402

Between two contacts : 5 λ

r403

Extra diffusion over contact: 2 λ

r404

Extra poly over contact: 2 λ

r405

Extra metal over contact: 2 λ

r406

Distance between contact and poly gate: 3 λ

r404 r402

r401

polysilicium

contact

r405 contact r403 r406

diffusion metal

gate

94

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11. Design Rules

11.9 Metal & Via Design Rules r501

Metal width : 4 λ

r502

Between two metals : 4 λ

r510


r601

Via width : 2 λ

r602

Between two Via: 5 λ

r603

Between Via and contact: 0 λ

r604

Extra metal over via: 2 λ

r605

Extra metal2 over via: 2 λ

r501

2

metal

r502

metal

r604 r602 via

metal2

r601

Stacked via over contact when r603 is 0

r603

When r603=0, stacked via over

contact

contact is allowed

11.10 Metal2 & Via2 Design Rules r701

Metal width: 4 λ

r702

Between two metal2 : 4 λ

r710


r801

Via2 width : 2 λ

r802

Between two Via2: 5 λ

r804

Extra metal2 over via2: 2 λ

r805


r701

metal2

2

r702

metal2

r804 r802 via2

Metal3

r801

11.11 Metal3 & Via3 Design Rules r901

Metal3 width: 4 λ

r902


r910


95

r901

2

metal3

r902

metal3

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11. Design Rules ra04

ra01

Via3 width : 2 λ

ra02


ra04


ra05


ra02 via3

Metal3,4

ra01

11.12 Metal4 & Via4 Design Rules rb01

Metal4 width: 4 λ

rb02


rb10


rc01

Via4 width : 2 λ

rc02


rc04


rc05


rb01 Metal4

2

rb02

Metal4

rc04 rc02 Via

Metal4,5

rc01

11.13 Metal5 & Via5 Design Rules rd01

Metal5 width: 8 λ

rd02


rd10


re01

Via5 width : 4 λ

re02


re04


re05


rd01

Metal5

2

rd02

Metal5

re04

re02

Via5

Metal5,6

re01

11.14 Metal6 Design Rules rf01

Metal6 width: 8 λ

rf02


rf10


96

rf01

2

Metal6

rf02

Metal6

18/05/02

VLSI Lab Compendium

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