vlsi manual

SREE SASTHA INSTITUTE OF

ENGINEERING AND

TECHNOLOGY,

CHEMBARAMBAKKAM

DEPARTMENT OF ELECTRONICS AND COMMUNICATION

ENGINEERING

LAB MANUAL

LAB CODE & NAME: EC2357 & VLSI DESIGN LAB

VI SEMESTER

2011 - 2012

PREPARED BY: K.SUJA & R.ANURADHA

VLSI LAB MANUAL

ANNA UNIVERSITY SYLLABUS EC2357 VLSI DESIGN LAB

1. Design Entry and simulation of combinational logic circuits (8 bit adders, 4

bit multipliers, address decoders, multiplexers), Test bench creation, functional

verification, and concepts of concurrent and sequential execution to be highlighted.

2. Design Entry and simulation of sequential logic circuits (counters, PRBS

generators, accumulators). Test bench creation, functional verification, and concepts

of concurrent and sequential execution to be highlighted.

3. Synthesis, P&R and Post P&R simulation for all the blocks/codes developed

in Expt. No. 1 and No. 2 given above. Concepts of FPGA floor plan, critical path,

design gate count, I/O configuration and pin assignment to be taught in this

experiment.

4. Generation of configuration/fuse files for all the blocks/codes developed as

part of Expt.1. and Expt. 2. FPGA devices must be configured and hardware tested

for the blocks/codes developed as part of Expt. 1. and Expt. 2. The correctness of the

inputs and outputs for each of the blocks must be demonstrated at least on

oscilloscopes (logic analyzer preferred).

5. Schematic Entry and SPICE simulation of MOS differential amplifier.

Determination of gain, bandwidth, output impedance and CMRR.

6. Layout of a simple CMOS inverter, parasitic extraction and simulation.

7. Design of a 10 bit number controlled oscillator using standard cell approach,

simulation followed by study of synthesis reports.

8. Automatic layout generation followed by post layout extraction and

simulation of the circuit studied in Expt. No.7

Note 1. For Expt. 1 To 4 can be carried out using Altera (Quartus) / Xilinx

(Alliance) / ACTEL (Libero) tools.

Note 2. For expt. 5-8 introduce the student to basics of IC design. These have to

be carried out using at least 0.5u CMOS technology libraries. The S/W tools needed

Cadence / MAGMA / Tanner.

TOTAL= 45 PERIODS

VLSI LAB MANUAL

CONTENTS

1) Study of Simulation using tools.

2) Design Entry and Simulation of Combinational Logic Circuits

a) Basic logic gates

b) Half adder and full adder

c) Half Subtractor and full Subtractor

d) 8 bit adder

e) 4 bit multiplier

f) Encoder and Decoder

g) Address Decoder

h) Multiplexer

3) Design Entry and Simulation of Sequential Logic Circuits

a) Flip-Flops

b) Counter

c) PRBS generator

d) Accumulator

4) Study of Synthesis tools

5) Place and Route and Back annotation for FPGAs

6) Schematic Entry and SPICE Simulation

a) CMOS Inverter

b) Universal Gate

c) Differential Amplifier

7) Layout of a CMOS Inverter

8) Design of a 10 bit number controlled oscillator

9) Automatic Layout Generation

VLSI LAB MANUAL

VLSI DESIGN

VLSI LAB MANUAL

ASIC DESIGN FLOW

VLSI LAB MANUAL

Fig 1: Waveform Editor - Initialize Timing Dialog Box

VLSI LAB MANUAL

Expt. No : STUDY OF SIMULATION TOOLS

Date :

AIM:

To study the Simulation tools.

THEORY:

Creating a Test Bench for Simulation:

In this section, you will create a test bench waveform containing

input stimulus you can use to simulate the counter module. This test

bench waveform is a graphical view of a test bench. It is used with a

simulator to verify that the counter design meets both behavioral and

timing design requirements. You will use the Waveform Editor to create a

test bench waveform (TBW) file.

1. Select the counter HDL file in the Sources in Project window.

2. Create a new source by selecting Project - New Source.

3. In the New Source window, select Test Bench Waveform as

the source type, and type test bench in the File Name field.

4. Click Next.

5. The Source File dialog box shows that you are associating the

test bench with the source file: counter.v Click Next.

6. Click Finish. You need to set initial values for your test bench

waveform in the Initialize Timing dialog box before the test

bench waveform editing window opens.

7. Fill in the fields in the Initialize Timing dialog box using

the information below:

Clock Time High: 20 ns.

Clock Time Low: 20 ns.

Input Setup Time: 10 ns.

Output Valid Delay: 10 ns.

VLSI LAB MANUAL

Initial Offset: 0 ns

Global Signals: GSR (FPGA)

Leave the remaining fields with their default values.

8. Click OK to open the waveform editor. The blue shaded areas are

associated with each input signal and correspond to the Input Setup Time

in the Initialize Timing dialog box. In this tutorial, the input transitions

occur at the edge of the blue cells located under each rising edge of the

CLOCK input.

Fig 2: Waveform Editor - Test Bench

9. In this design, the only stimulus that you will provide is on the

DIRECTION port. Make the transitions as shown below for the

DIRECTION port:

Click on the blue cell at approximately the 300 ns clock transition. The

signal switches to high at this point.

Click on the blue cell at approximately the 900 ns clock transition. The

signal switches back to low.

Click on the blue cell at approximately the 1400 ns clock

transition. The signal switches to high again.

10. Select File - Save to save the waveform. In the Sources in Project

window, the TBW file is automatically added to your project.

11. Close the Waveform Editor window.

VLSI LAB MANUAL

Simulating the Behavioral Model (ISE Simulator):

If you are using ISE Base or Foundation, you can simulate your design with the

ISE Simulator. If you wish to simulate your design with a ModelSim simulator,

skip this section and proceed to the “Simulating the Behavioral Model

(ModelSim)” section.

Fig 3: Simulator Processes for Test Bench

VLSI LAB MANUAL

Fig 4: Behavioral Simulation in ISE Simulator

To run the integrated simulation processes in ISE:

1. Select the test bench waveform in the Sources in Project window. You can

see the Xilinx ISE Simulator processes in the Processes for Source window.

2. Double-click the Simulate Behavioral Model process. The ISE Simulator

opens and runs the simulation to the end of the test bench.

3. To see your simulation results, select the test bench tab and zoom in on the

transitions. You can use the zoom icons in the waveform view, or right click

and select a zoom command. The ISE window, including the waveform view.

4. Zoom in on the area between 300 ns and 900 ns to verify that the

counter is counting up and down as directed by the stimulus on the

DIRECTION port.

5. Close the waveform view window. You have completed simulation of your

design using the ISE Simulator.

VLSI LAB MANUAL

Simulating the Behavioral Model (ModelSim):

If you have a ModelSim simulator installed, you can simulate your design using

the integrated ModelSim flow. You can run processes from within ISE which

launches the installed ModelSim simulator.

To run the integrated simulation processes in ISE:

1. Select the test bench in the Sources in Project window. You can see

ModelSim Simulator processes in the Processes for Source window in Fig

4.

Fig 5: Simulator Processes for Test Bench

VLSI LAB MANUAL

Fig 6: Behavioral Simulation in ModelSim

2. Double-click the Simulate Behavioral Model process. The ModelSim

simulator opens and runs your simulation to the end of the test bench. The

ModelSim window, including the waveform, should look like

Fig 6.

To see your simulation results, view the Wave window.

1. Right-click in the Wave window and select a zoom command.



DIRECTION port.

3. Close the ModelSim window.

RESULT:

VLSI LAB MANUAL

Design Entry and Simulation of Combinational Logic Circuits Expt. No : BASIC LOGIC GATES

Date :

AIM:

To implement basic logic gates using Verilog HDL.

APPARATUS REQUIRED:

PC with Windows XP.

XILINX, ModelSim software.

FPGA kit.

RS 232 cable.

PROCEDURE:

Write and draw the Digital logic system.

Write the Verilog code for above system.

Enter the Verilog code in Xilinx software.

Check the syntax and simulate the above Verilog code (using

ModelSim or Xilinx) and verify the output waveform as obtained.

Implement the above code in Spartan III using FPGA kit.

VLSI LAB MANUAL

PROGRAM: AND Gate:

// Module Name: Andgate

module Andgate (i1, i2,out);

input i1, i2;

output out;

and (out,i1,i2);

endmodule

// Module Name: Stimulus.v module

module stimulus;

//Inputs

reg i1, i2;

//Outputs

wire out;

// Instantiate the Unit Under Test (UUT)

Andgate uut1 (.i1(i1),.i2(i2),.out(out));

initial

begin

$display("\t\t\t\tAND Gate");

$display("\t\t--------------------------------------");

$display("\t\tInput1\t\t Input2\t\t Output");

$display("\t\t--------------------------------------");

$monitor("\t\t\t%b\t\t%b\t\t%b ",i1,i2,out);

#4 $display("\t\t--------------------------------------");

end

initial

begin

VLSI LAB MANUAL

i1=1'b0; i2=1'b0; #1 i2=1'b1;

#1 i1=1'b1; i2=1'b0; #1 i1=1'b1; i2=1'b1; #1

$stop;

end

endmodule

Symbol

TRUTH TABLE

--------------------------------------

Input1 Input2 Output

--------------------------------------

0 0 0

0 1 0

1 0 0

1 1 1

--------------------------------------

Simulated Waveform

VLSI LAB MANUAL

PROGRAM OR Gate:

// Module Name: Orgate

module Orgate (i1, i2,out);

input i1, i2;

output out;

or (out,i1,i2);

endmodule


module stimulus;

//Inputs

reg i1, i2;

//Outputs

wire out;


Orgate uut1 (.i1(i1),.i2(i2),.out(out));

initial

begin

$display("\t\t\t\tORGate");

$display("\t\t--------------------------------------");


$display("\t\t--------------------------------------");


#4 $display("\t\t--------------------------------------");

end

initial

begin

VLSI LAB MANUAL

i1=1'b0; i2=1'b0; #1 i2=1'b1;

#1 i1=1'b1; i2=1'b0; #1 i1=1'b1; i2=1'b1; #1

$stop;

end

endmodule

Symbol

TRUTH TABLE

--------------------------------------


--------------------------------------

0 0 0

0 1 1

1 0 1

1 1 1

--------------------------------------

Simulated Waveform

VLSI LAB MANUAL

PROGRAM NOR Gate:

// Module Name: Norgate

Module Norgate (i1, i2,out);

input i1, i2;

output out;

nor (out,i1,i2);

endmodule


module stimulus;

//Inputs

reg i1, i2;

//Outputs

wire out;


Norgate uut1 (.i1(i1),.i2(i2),.out(out));

initial

begin

$display("\t\t\t\tNORGate");

$display("\t\t--------------------------------------");


$display("\t\t--------------------------------------");


#4 $display("\t\t--------------------------------------");

end

initial

begin

i1=1'b0; i2=1'b0; #1 i2=1'b1;

VLSI LAB MANUAL

#1 i1=1'b1; i2=1'b0; #1 i1=1'b1; i2=1'b1; #1

$stop;

end

endmodule

Symbol

TRUTH TABLE

--------------------------------------


--------------------------------------

0 0 1

0 1 0

1 0 0

1 1 0

--------------------------------------

Simulated Waveform

VLSI LAB MANUAL

PROGRAM NAND Gate:

// Module Name: Nandgate

module Nandgate (i1, i2,out);

input i1, i2;

output out;

nand (out,i1,i2);

endmodule


module stimulus;

//Inputs

reg i1, i2;

//Outputs

wire out;


Nandgate uut1 (.i1(i1),.i2(i2),.out(out));

initial

begin

$display("\t\t\t\tNANDGate");

$display("\t\t--------------------------------------");


$display("\t\t--------------------------------------");


#4 $display("\t\t--------------------------------------");

end

initial

begin

i1=1'b0; i2=1'b0; #1 i2=1'b1;

VLSI LAB MANUAL

#1 i1=1'b1; i2=1'b0; #1 i1=1'b1; i2=1'b1; #1

$stop;

end

endmodule

Symbol

TRUTH TABLE

--------------------------------------


--------------------------------------

0 0 1

0 1 1

1 0 1

1 1 0

--------------------------------------

Simulated Waveform

VLSI LAB MANUAL

PROGRAM XOR Gate:

// Module Name: Xorgate

module Xorgate (i1, i2,out);

input i1, i2;

output out;

xor (out,i1,i2);

endmodule


module stimulus;

//Inputs

reg i1, i2;

//Outputs

wire out;


Xorgate uut1 (.i1(i1),.i2(i2),.out(out));

initial

begin

$display("\t\t\t\tXORGate");

$display("\t\t--------------------------------------");


$display("\t\t--------------------------------------");


#4 $display("\t\t--------------------------------------");

end

initial

begin

i1=1'b0; i2=1'b0; #1 i2=1'b1;

VLSI LAB MANUAL

#1 i1=1'b1; i2=1'b0; #1 i1=1'b1; i2=1'b1; #1

$stop;

end

endmodule

Symbol

TRUTH TABLE

--------------------------------------


--------------------------------------

0 0 0

0 1 1

1 0 1

1 1 0

--------------------------------------

Simulated Waveform

VLSI LAB MANUAL

PROGRAM XNOR Gate:

// Module Name: Xnorgate

module Xnorgate (i1, i2,out);

input i1, i2;

output out;

xnor (out,i1,i2);

endmodule


module stimulus;

//Inputs

reg i1, i2;

//Outputs

wire out;


Xnorgate uut1 (.i1(i1),.i2(i2),.out(out));

initial

begin

$display("\t\t\t\tXNORGate");

$display("\t\t--------------------------------------");


$display("\t\t--------------------------------------");


#4 $display("\t\t--------------------------------------");

end

initial

begin

i1=1'b0; i2=1'b0; #1 i2=1'b1;

VLSI LAB MANUAL

#1 i1=1'b1; i2=1'b0; #1 i1=1'b1; i2=1'b1; #1

$stop;

end

endmodule

Symbol

TRUTH TABLE

--------------------------------------


--------------------------------------

0 0 1

0 1 0

1 0 0

1 1 1

--------------------------------------

Simulated Waveform

VLSI LAB MANUAL

PROGRAM NOT Gate:

// Module Name: Notgate

module Notgate (i1, out);

input i1;

output out;

not (out,i1);

endmodule


module stimulus;

//Inputs

reg i1;

//Outputs

wire out;


Notgate uut1 (.i1(i1),. out(out));

initial

begin

$display("\t\t\t\tNOTGate");

$display("\t\t--------------------------------------");

$display("\t\tInput1\t\t Output");

$display("\t\t--------------------------------------");

$monitor("\t\t\t%b \t\t%b ",i1 ,out);

#4 $display("\t\t--------------------------------------");

end

initial

begin

i1=1'b0;

#1 i1=1'b1;

VLSI LAB MANUAL

#1 $stop;

end

endmodule

Symbol

TRUTH TABLE

--------------------------------------

Input1 Output

--------------------------------------

0 1

1 0

--------------------------------------

Simulated Waveform

VLSI LAB MANUAL

PROGRAM Buffer:

// Module Name: Buffer

module Buffer (i1, out);

input i1;

output out;

buf (out,i1);

endmodule


module stimulus;

//Inputs

reg i1;

//Outputs

wire out;


Buffer uut1 (.i1(i1),. out(out));

initial

begin

$display("\t\t\t\tBuffer");

$display("\t\t--------------------------------------");

$display("\t\tInput1\t\t Output");

$display("\t\t--------------------------------------");

$monitor("\t\t\t%b \t\t%b ",i1 ,out);

#4 $display("\t\t--------------------------------------");

end

initial

begin

i1=1'b0;

#1 i1=1'b1;

VLSI LAB MANUAL

#1 $stop;

end

endmodule

Symbol

TRUTH TABLE

--------------------------------------

Input1 Output

--------------------------------------

0 0

1 1

--------------------------------------

Simulated Waveform

RESULT:

VLSI LAB MANUAL

Expt. No: HALF ADDER AND FULL ADDER

Date :

AIM:

To implement half adder and full adder using Verilog HDL.

APPARATUS REQUIRED:

PC with Windows XP


FPGA kit

RS 232 cable.

PROCEDURE:




Check the syntax and simulate the above Verilog code (using ModelSim

or Xilinx) and verify the output waveform as obtained.

Implement the above code in Spartan III using FPGA kit

VLSI LAB MANUAL

PROGRAM:

Half Adder:

// Module Name: HalfAddr

module HalfAddr(sum, c_out, i1, i2);

output sum, c_out;

input i1; input i2;

xor(sum,i1,i2);

and(c_out,i1,i2);

endmodule

// Module Name: Stimulus.v

module Stimulus_v;

// Inputs

reg i1,i2;

// Outputs

wire sum, c_out;


HalfAddr uut (.sum(sum),.c_out(c_out),.i1(i1),.i2(i2));

initial

begin

$display("\t\t\Half Adder");

$display("\t\tInput1\t\t Input2\t\t Carry\t\t Sum");

$display("\t\t----------------------------------------");

$monitor(“\%b\t\t%b\t\t%b\t\t”,i1,i2,c_out,sum);

$display("\t\t ---------------------------------------“);

end

initial

begin

i1=1'b0; i2=1'b0; #1 i2=1'b1;

VLSI LAB MANUAL

#1 i1=1'b1; i2=1'b0; #1 i1=1'b1; i2=1'b1;

#1 $stop;

end

endmodule

LOGIC DIAGRAM: TRUTH TABLE: --------------------------------------------------

Input1 Input2 Sum C_out

---------------------------------------------------

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

----------------------------------------------------

SIMULATED WAVEFORM:

VLSI LAB MANUAL

PROGRAM Full Adder: // Module Name: FullAddr

module FullAddr(i1, i2, c_in, c_out, sum);

input i1, i2, c_in;

output c_out, sum;

wire s1,c1,c2;

xor n1(s1,i1,i2);

and n2(c1,i1,i2);

xor n3(sum,s1,c_in);

and n4(c2,s1,c_in);

or n5(c_out,c1,c2);

endmodule


module Stimulus_v;

// Inputs

reg i1 , i2 , c_in;

// Outputs

wire c_out, sum;


FullAddr uut (.i1(i1),.i2(i2),.c_in(c_in),.c_out(c_out),.sum(sum));

initial

begin

$display("\t\t\t\t\t\tFull Adder");

$display("\t\t----------------------------------------------------------------");

$display("\t\ti1\t\ti2\t\tC_in\t\t\tC_out\t\tSum");

$display("\t\t----------------------------------------------------------------");

VLSI LAB MANUAL

$monitor(" t\t%b\t\t%b\t\t%b\t\t\t%b\t\t%b",i1,i2,c_in,c_out,sum);

#9 $display("\t\t-------------------------------------------------------------------");

end

initial

begin

#1i1 = 0;i2 = 0;c_in = 0;

#1 i1 = 0;i2 = 0;c_in = 0;

#1 i1 = 0;i2 = 0;c_in = 1;

#1 i1 = 0;i2 = 1;c_in = 0;

#1 i1 = 0;i2 = 1;c_in = 1;

#1 i1 = 1;i2 = 0;c_in = 0;

#1 i1 = 1;i2 = 0;c_in = 1;

#1 i1 = 1;i2 = 1;c_in = 0;

#1 i1 = 1;i2 = 1;c_in = 1;

#2 $stop;

end

endmodule

LOGIC DIAGRAM:

VLSI LAB MANUAL

TRUTH TABLE: ----------------------------------------------

Input1 Input2 C_in Sum C_out

--------------------------------------------------

0 0 0 0 0

0 0 1 1 0 \

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Expt. No: HALF SUBTRACTOR & FULL SUBTRACTOR

Date :

AIM:

To implement half subtractor and full subtractor using Verilog HDL.

APPARATUS REQUIRED:

PC with Windows XP


FPGA kit

RS 232 cable.

PROCEDURE:




Check the syntax and simulate the above verilog code (using ModelSim or

Xilinx) and verify the output waveform as obtained.


VLSI LAB MANUAL

PROGRAM:

Half Subtractor:

// Module Name: HalfSub

module HalfSub(i0, i1, bor, dif);

input i0, i1;

output bor,

dif;

wire i0n;

not(i0n,i0);

xor(dif,i0,i1);

and(bor,i0n,i1);

endmodule

// Module

Name:Stimulus.v

module Stimulus_v;

// Inputs

reg i0, i1;

// Outputs

wire bor; wire dif;


HalfSub uut (.i0(i0),.i1(i1),.bor(bor),.dif(dif));

initial

begin

$display("\t\t\t\t\tHalf Subtractor");

$display("\t\t----------------------------------------------------------");

$display("\t\tInput1\t\t Input2\t\t Borrow\t\t Difference");

$display("\t\t----------------------------------------------------------");

$monitor("\t\t\t%b\t\t%b\t\t%b\t\t%b",i0,i1,bor,dif);

VLSI LAB MANUAL

#4 $display("\t\t-----------------------------------------------------------");

end initial

begin

i0=1'b0; i1=1'b0;

#1 i1=1'b1;

#1 i0=1'b1; i1=1'b0;

#1 i0=1'b1;

i1=1'b1; #1

$stop;

end

endmodule

Logic Diagram:

TRUTH TABLE: --------------------------------------------------

Input1 Input2 bor dif

---------------------------------------------------

0 0 0 0

0 1 1 1

1 0 1 0

1 1 0 1

----------------------------------------------------

VLSI LAB MANUAL

SIMULATED WAVEFORM

PROGRAM

Full Subtractor:

// Module Name: FullSub

module FullSub(b_in, i1, i0, b_out, dif); input b_in;

input i1, i0;

output

b_out,dif;

assign {b_out,dif}=i0-i1-b_in;

endmodule


module Stimulus_v;

// Inputs

reg b_in, i1,i0;

// Outputs

wire b_out;

wire dif;


FullSub uut (.b_in(b_in),.i1(i1),.i0(i0),.b_out(b_out),.dif(dif));

initial

VLSI LAB MANUAL

begin

$display("\t\t\t\t\t\tFull Subtractor");

$display("\t\t-------------------------------------------------------------------------");

$display("\t\tB_in\t\tI1\t\ti0\t\t\tB_out\t\tDifference");

$display("\t\t-------------------------------------------------------------------------");

$monitor("\t\t%b\t\t%b\t\t%b\t\t\t %b\t\t\t %b",b_in,i1,i0,b_out,dif);

#9 $display("\t\t-------------------------------------------------------------------------");

end

initial

begin

// Initialize Inputs

b_in = 0;i1 = 0;i0 = 0;

#1 b_in = 0;i1 = 0;i0 = 0;

#1 b_in = 0;i1 = 0;i0 = 1;

#1 b_in = 0;i1 = 1;i0 = 0;

#1 b_in = 0;i1 = 1;i0 = 1;

#1 b_in = 1;i1 = 0;i0 = 0;

#1 b_in = 1;i1 = 0;i0 = 1;

#1 b_in = 1;i1 = 1;i0 = 0;

#1 b_in = 1;i1 = 1;i0 = 1;

#2 $stop;

end

endmodule

VLSI LAB MANUAL

LOGIC DIAGRAM:

TRUTH TABLE:

----------------------------------------------

Input1 Input2 C_in Diff Borr

--------------------------------------------------

0 0 0 0 0

0 0 1 1 1 \

0 1 0 1 1

0 1 1 0 1

1 0 0 1 0

1 0 1 0 0

1 1 0 0 0

1 1 1 1 1

VLSI LAB MANUAL

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Expt. No: 4 BIT MULTIPLIER

Date :

AIM:

To implement four bit multiplier using Verilog.

APPARATUS REQUIRED:

PC with Windows XP

XILINX, ModelSim software

FPGA kit

RS 232 cable.

PROCEDURE:




Check the syntax and simulate the above verilog code (using



VLSI LAB MANUAL

PROGRAM

MULTIPLIER

module multi(a,b, c);

input [3:0] a,b;

output [7:0] c;

assign c = a * b;

endmodule

STIMULUS

module testbenchmulti ;

//inputs

reg [3:0] a,b;

//outputs

wire [7:0] c;

multi multipl(.c(c),.a(a),.b(b));

initial

begin

a=4'b0; b=4'b0;

//wait 100ns for global reset to finish

#100; a=4'd3; b=4'd4;

#100; a=4'd3; b=4'd5;

#100; a=4'd2; b=4'd4;

end

endmodule

VLSI LAB MANUAL

BLOCK DIAGRAM:

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Expt. No: 8 BIT ADDER

Date :

AIM:

To implement the 8-bit adder using Verilog.

APPARATUS REQUIRED:

PC with Windows XP

XILINX, ModelSim software

FPGA kit

RS 232 cable.

PROCEDURE:




Check the syntax and simulate the above verilog code (using ModelSim

or Xilinx) and verify the output waveform as obtained.


VLSI LAB MANUAL

PROGRAM

8 BIT ADDER

module adder(a,b, s,c);

input [7:0] a,b;

output [7:0] s,c;

assign {c,s} = a + b;

endmodule

STIMULUS:

module testbenadder;

//Inputs

reg [7:0] a,b;

//outputs

wire [7:0] s;

wire c;

adder add(.s(s),.c(c),.a(a),.b(b));

initial

begin

//initialize input

a=8'd0; b=8'd0;

//wait 100ns for global reset to finish

#100; a=8'd1; b=8'd0;

#100; a=8'd9; b=8'd5;

#100; a=8'd5; b=8'd7;

end

endmodule

VLSI LAB MANUAL

BLOCK DIAGRAM:

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Expt No: IMPLEMENTATION OF 4x2 ENCODER AND

Date: 2x4 DECODER

AIM:

To implement 4x2 Encoder and 2 x 4 Decoder Verilog HDL.

APPARATUS REQUIRED:

PC with Windows XP.


FPGA kit.

RS 232 cable.

PROCEDURE:







VLSI LAB MANUAL

PROGRAM:

Encoder:

// Module Name: Encd2to4

module Encd2to4(i0, i1, i2, i3, out0, out1);

input i0,i1, i2, i3;

output out0, out1;

reg out0,out1;

always@(i0,i1,i2,i3

)

case({i0,i1,i2,i3})

4'b1000:{out0,out1}=2'b00;

4'b0100:{out0,out1}=2'b01;

4'b0010:{out0,out1}=2'b10;

4'b0001:{out0,out1}=2'b11;

default: $display("Invalid");

endcase

endmodule


module Stimulus_v;

// Inputs

reg i0, i1, i2, i3;

// Outputs

wire out0, out1;


Encd2to4 uut(.i0(i0),.i1(i1),.i2(i2),.i3(i3),.out0(out0),.out1(out1));

initial

begin

VLSI LAB MANUAL

$display("\t\t 4to2 Encoder");

$display("\t\t------------------------------");

$display("\t\tInput\t\t\tOutput");

$display("\t\t------------------------------");

$monitor("\t\t%B%B%B%B\t\t\t %B%B",i0,i1,i2,i3,out0,out1);

#4 $display("\t\t-------------------------------");

end

initial

begin

i0=1; i1=0; i2=0; i3=0;

#1 i0=0; i1=1; i2=0; i3=0;

#1 i0=0; i1=0; i2=1; i3=0;

#1 i0=0; i1=0; i2=0; i3=1;

#1 $stop;

end

endmodule

BLOCK DIAGRAM:

VLSI LAB MANUAL

TRUTH TABLE

Output: 4to2 Encoder

----------------------------------

Input Output

----------------------------------

1000 00

0100 01

0010 10

0001 11

SIMULATED WAVEFORM:

VLSI LAB MANUAL

PROGRAM

Decoder:

// Module Name: Decd2to4

module Decd2to4(i0, i1, out0, out1, out2, out3);

input i0, i1;

output out0, out1, out2, out3;

reg

out0,out1,out2,out3;

always@(i0,i1)

case({i0,i1})

2'b00:

{out0,out1,out2,out3}=4'b1000;

2'b01:


2'b10:


2'b11:


default:

$display("Invalid");

endcase

endmodule

VLSI LAB MANUAL


module Stimulus_v;

// Inputs

reg i0, i1;

// Outputs

wire out0, out1, out2, out3;


Decd2to4 uut (.i0(i0),.i1(i1),.out0(out0),.out1(out1),.out2(out2),.out3(out3));

initial

begin

$display(“\t\t 2to4 Decoder”);

$display(“\t\t --------------------------”);

$display(“\t\t Input \t\t Output”);

$display(“\t\t --------------------------”);

$monitor(“\t\t %b%b\t\t\t %b%b%b %b”,i0,i1,out0,out1,out2,out3);

#4 $display(“\t\t --------------------------”);

end

initial

begin

i0=0;i1=0;

#1 i0=0;i1=1;

#1 i0=1;i1=0;

#1 i0=1;i1=1;

#1 $stop;

end

endmodule

VLSI LAB MANUAL

TRUTH

TABLE

Output: 2to4 Decoder

----------------------------------

Input Output

----------------------------------

00 1000

01 0100

02 0010

03 0001

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Expt. No: MULTIPLEXER & DEMULTIPLEXER

Date :

AIM:

To implement Multiplexer & Demultiplexer using Verilog HDL.

APPARATUS REQUIRED:

PC with Windows XP.


FPGA kit.

RS 232 cable.

PROCEDURE:







VLSI LAB MANUAL

PROGRAM:

Multiplexer:

// Module Name: Mux4to1

module Mux4to1(i0, i1, i2, i3, s0, s1, out);

input i0, i1, i2, i3, s0, s1;

output out;

wire s1n,s0n;

wire y0,y1,y2,y3;

not (s1n,s1);

not (s0n,s0);

and (y0,i0,s1n,s0n);

and (y1,i1,s1n,s0);

and (y2,i2,s1,s0n);

and (y3,i3,s1,s0);

or (out,y0,y1,y2,y3);

endmodule

VLSI LAB MANUAL


module Stimulus_v;

// Inputs

reg i0, i1, i2,,i3, s0, s1;

// Outputs

wire out;

Instantiate the Unit Under Test (UUT)

Mux4to1 uut (.i0(i0),.i1(i1),.i2(i2),.i3(i3),.s0(s0),.s1(s1),.out(out));

initial

begin

$display(“\t\t\t4to1 Multiplexer”);

$display(“\t\t-------------------------“);

#1 $display(“\t\t\t Input=%b%b%b%b”,i0,i1,i2,i3);

$display(“\t\t----------------------------------“);

$display(“\t\tSelector \t\t\t\t Output”);

$display(“\t\t----------------------------------“);

$monitor(“\t\t{%b,%b}\t\t\t\t%b”,s0,s1,out);

#4 $display(“\t\t-----------------------------------------------“);

end initial begin

i0=1; i1=0; i2=1; i3=1;

#1 s0=0; s1=0;

#1 s0=1; s1=0;

#1 s0=0; s1=1;

#1 s0=1; s1=1;

#1 $stop;

end

endmodule

VLSI LAB MANUAL

LOGIC DIAGRAM:

TRUTH TABLE:

4to1 Multiplexer

--------------------------------

Input = 1011

--------------------------------

Status Output

--------------------------------

{0,0} 1

{0,1} 0

{1,0} 1

{1,1} 1

VLSI LAB MANUAL

SIMULATED WAVEFORM:

PROGRAM

Demultiplexer:

// Module Name: Dux1to4

module Dux1to4(in, s0, s1, out0, out1, out2, out3);

input in, s0, s1;

output out0, out1, out2,out3;

wire s0n,s1n;

not(s0n,s0);

not(s1n,s1);

and (out0,in,s1n,s0n);

and (out1,in,s1n,s0);

and (out2,in,s1,s0n);

and (out3,in,s1,s0);

endmodule

VLSI LAB MANUAL


module Stimulus_v;

//Inputs

reg in, s0, s1;

// Outputs

wire out0, out1, out2, out3;


Dux1to4 uut (.in(in),.s0(s0),.s1(s1),.out0(out0),.out1(out1),.out2(out2),

.out3(out3));

initial

begin

$display("\t\t 1to4 Demultiplexer");

$display("\t\t------------------------------------");

#1 $display("\t\t\t\tInput=%b",in);

$display("\t\t------------------------------------");

$display("\t\tStatus\t\t\t\tOutput");

$display("\t\t------------------------------------");

$monitor("\t\t{%b,%b}\t\t\t\t%b%b%b%b",s1,s0,out0,out1,out2,out3);

#4 $display("\t\t------------------------------------");

end

initial

begin

in=1;#1 s1=0;s0=0;

#1 s1=0;s0=1; #1 s1=1;s0=0;

#1 s1=1;s0=1; #1 $stop;

end

endmodule

VLSI LAB MANUAL

TRUTH TABLE:

1 to 4 Demultiplexer

--------------------------------

Input = 1

--------------------------------

Status Output

--------------------------------

{0,0} 1000

{0,1} 0100

{1,0} 0010

{1,1} 0001

LOGIC DIAGRAM:

VLSI LAB MANUAL

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Design Entry and Simulation of Sequential Logic Circuits Expt. No : Flip - Flops

Date :

AIM:

To implement flip – flops using Verilog HDL.

APPARATUS REQUIRED:

PC with Windows XP.


FPGA kit.

RS 232 cable.

PROCEDURE:







VLSI LAB MANUAL

PROGRAM:

D Flip-Flop:

// Module Name: DFF

module DFF(Clock, Reset, d,

q);

input Clock;

input Reset;

input d; output

q;

reg q;

always@(posedge Clock or negedge

Reset) if (~Reset)

q=1'b0;

else

q=d;

endmodule


module Stimulus_v;

// Inputs

reg Reset;

reg Clock;

reg d;

// Outputs

wire q;


DFF uut (.Clock(Clock),.Reset(Reset),.d(d),.q(q));

initial

begin

VLSI LAB MANUAL

$display("\t\t\t\t\tD FipFlop");

$display("\t\t------------------------------------------------------------");

$display("\t\tClock\t\tReset\t\tInput (d)\t\tOutput q(~q)");

$display("\t\t------------------------------------------------------------");

$monitor("\t\t %d \t\t %d \t\t %d \t\t

%d(%d)",Clock,Reset,d,q,~q);

#15 $display("\t\t------------------------------------------------------------");

end

always

#1 Clock=~Clock;

initial

begin

Clock=0;Reset=0;d=0;

#2 Reset=0;d=1;

#2 d=0;

#2 Reset=1; d=1;

#2 d=0; #2 d=1;

#2 Reset=0; d=0;

#1; // Gap for display.

#2 $stop;

end

endmodule

LOGIC DIAGRAM:

VLSI LAB MANUAL

TRUTH TABLE:

D FipFlop

Clock Reset Input (d) Output q(~q)

0 0 0 0(1)

1 0 0 0(1)

0 0 1 0(1)

1 0 1 0(1)

0 0 0 0(1)

1 0 0 0(1)

0 1 1 0(1)

1 1 1 1(0)

0 1 0 1(0)

1 1 0 0(1)

0 1 1 0(1)

1 1 1 1(0)

0 0 0 0(1)

1 0 0 0(1)

0 0 0 0(1)

SIMULATED WAVEFORM:

VLSI LAB MANUAL

T Flip-Flop:

// Module Name: TFF

module TFF(Clock, Reset, t,

q);

input Clock, Reset, t;

output q;

reg q;

always@(posedge Clock , negedge Reset)

if(~Reset)

q=0;

else if (t)

q=~q;

else

q=q;

endmodule


module Stimulus_v;

// Inputs

reg Clock, Reset, t;

// Outputs

wire q;

// Instantiate the Unit Under Test UUT)

TFF uut (.Clock(Clock),.Reset(Reset),.t(t),.q(q));

initial

begin

$display("\t\t\t\t\tT FipFlop");

$display("\t\t------------------------------------------------------------");

VLSI LAB MANUAL

$display("\t\tClock\t\tReset\t\tInput (t)\t\tOutput q(~q)");

$display("\t\t------------------------------------------------------------");

$monitor("\t\t %d \t\t %d \t\t %d \t\t

%d(%d)",Clock,Reset,t,q,~q);

#15 $display("\t\t------------------------------------------------------------");

end

always

#1 Clock=~Clock;

initial

begin

Clock=0; Reset=0;t=0;

#2 Reset=0; t=1;

#2 t=0;

#2 Reset=1; t=1;

#2 t=0;

#2 t=1;

#2 Reset=0; t=0;


#2 $stop;

end

endmodule

LOGIC DIAGRAM:

VLSI LAB MANUAL

TRUTH TABLE:

Clock Reset Input (t) Output q(~q)

0 0 0 0(1)

1 0 0 0(1)

0 0 1 0(1)

1 0 1 0(1)

0 0 0 0(1)

1 0 0 0(1)

0 1 1 0(1)

1 1 1 1(0)

0 1 0 1(0)

1 1 0 1(0)

0 1 1 1(0)

1 1 1 0(1)

0 0 0 0(1)

1 0 0 0(1)

0 0 0 0(1)

SIMULATED WAVEFORM

VLSI LAB MANUAL

Program:

JK Flip-Flop:

// Module Name: JKFF

module JKFF(Clock, Reset, j, k, q);

input Clock, Reset, j, k; output q;

reg q;

always@(posedge Clock, negedge Reset)

if(~Reset)

q=0;

else begin

case({j,k})

2'b00: q=q;

2'b01: q=0;

2'b10:

q=1;

2’b11: q=~q;

endcase

end

endmodule


module Stimulus_v;

// Inputs

reg Clock, Reset, j, k;

// Outputs

wire q;


VLSI LAB MANUAL

JKFF uut (.Clock(Clock),.Reset(Reset),.j(j),.k(k),.q(q));

initial

begin

$display("\t\t\t\t\tJK FipFlop");

$display("\t\t--------------------------------------------------------------");

$display("\t\tClock\t\tReset\t\tInput (j,k)\t\tOutput q(~q)");

$display("\t\t--------------------------------------------------------------");

$monitor("\t\t %d \t\t %d \t\t (%d,%d) \t\t%d(%d)",Clock,Reset,j,k,q,~q);

#19 $display("\t\t--------------------------------------------------------------");

end

always

#1 Clock=~Clock;

initial

begin

Clock=0; Reset=0;j=0; k=0;

#2 j=0; k=1;

#2 j=1; k=0;

#2 j=1; k=1;

#2 Reset=1;j=0; k=0;

#2 j=0; k=1;

#2 j=1; k=0;

#2 j=1; k=1;

#2 Reset=0; j=0; k=0;


#2 $stop;

end

endmodule

VLSI LAB MANUAL

LOGIC DIAGRAM:

TRUTH TABLE:

Clock Reset Input (j,k) Output q(~q)

0 0 (0,0) 0(1)

1 0 (0,0) 0(1)

0 0 (0,1) 0(1)

1 0 (0,1) 0(1)

0 0 (1,0) 0(1)

1 0 (1,0) 0(1)

0 0 (1,1) 0(1)

1 0 (1,1) 0(1)

0 1 (0,0) 0(1)

1 1 (0,0) 0(1)

0 1 (0,1) 0(1)

1 1 (0,1) 0(1)

0 1 (1,0) 0(1)

1 1 (1,0) 1(0)

0 1 (1,1) 1(0)

1 1 (1,1) 0(1)

0 0 (0,0) 0(1)

1 0 (0,0) 0(1)

0 0 (0,0) 0(1)

VLSI LAB MANUAL

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Expt. No: PRBS GENERATORS

Date :

AIM:

To implement the PRBS generators using Verilog HDL.

APPARATUS REQUIRED:

PC with Windows XP.


FPGA kit.

RS 232 cable.

PROCEDURE:







VLSI LAB MANUAL

PROGRAM

PRBS GENERATOR:

module prbs(a,clk,clr);

output [3:0] a;

input clk,clr;

reg [3:0] tmp;

always @(posedge clk or posedge clr)

begin

if(clr)

begin

tmp = 4'b1111;

end

else

begin

tmp = { tmp[0]^tmp[1],tmp[3],tmp[2],tmp[1]};

end

end

assign a=tmp;

endmodule

STIMULUS MODULE

module main;

reg clk, reset;

wire rand;

prbs pr (rand, clk, reset);

initial

begin

forever

VLSI LAB MANUAL

begin

clk <= 0;

#5 clk <= 1;

#5 clk <= 0;

end

end

initial

begin

reset = 1;

#12 reset = 0;

#90 reset = 1;

#12 reset = 0;

end

endmodule

BLOCK DIAGRAM:

VLSI LAB MANUAL

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Expt. No: ACCUMULATOR

Date :

AIM:

To implement the Accumulator using Verilog HDL.

APPARATUS REQUIRED:

PC with Windows XP.


FPGA kit.

RS 232 cable.

PROCEDURE:







VLSI LAB MANUAL

PROGRAM

ACCUMULATOR:

module acc(indata, clk,clr, outdata);

input [3:0] indata;

input clk,clr;

output [3:0] outdata;

reg [3:0] outdata;

always@(posedge clk or posedge clr)

begin

if(clr)

outdata <= 4'd0;

else

outdata <= indata;

end

endmodule

stimulus

module testbenchacc;

//input [3:0] indata;

//input clk,clr;

reg [3:0] indata;

reg clk,clr;

VLSI LAB MANUAL

//output [7:0] outdata;

wire [3:0] outdata;

//Instantiate unit under test (uut)

acc uut (.indata(indata),.clk(clk),.clr(clr),.outdata(outdata));

initial

begin

//Initialize Inputs

indata = 4'd0;

clk = 1'b0;

clr = 1'b1;

#50; indata = 4'd4; clk = 1'b1; clr = 1'b0;









end

endmodule

VLSI LAB MANUAL

BLOCK DIAGRAM:

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Expt. No: IMPLEMENTATION OF COUNTERS

Date:

AIM:

To implement Counters using Verilog HDL

APPARATUS REQUIRED:

PC with Windows XP.


FPGA kit.

RS 232 cable.

PROCEDURE:







VLSI LAB MANUAL

PROGRAM:

2- Bit Counter:

// Module Name: Count2Bit

module Count2Bit(Clock, Clear, out);

input Clock, Clear;

output [1:0] out;

reg [1:0]out;

always@(posedge Clock, negedge Clear)

if((~Clear) || (out>=4))

out=2'b00;

else

out=out+1;

endmodule


module Stimulus_v;

// Inputs

reg Clock, Clear;

// Outputs

wire [1:0] out;


Count2Bit uut (.Clock(Clock),.Clear(Clear),.out(out));

initial

begin

$display("\t\t\t 2 Bit Counter");

$display("\t\t----------------------------------------");

$display("\t\tClock\t\tClear\t\tOutput[2]");

$display("\t\t----------------------------------------");

$monitor("\t\t %b\t\t %b \t\t %b ",Clock,Clear,out);

VLSI LAB MANUAL

#28 $display("\t\t----------------------------------------");

end

always

#1 Clock=~Clock;

initial

begin

Clock=0; Clear=0;

#10 Clear=1;

#18 Clear=0;

#2 $stop;

end

endmodule

LOGIC DIAGRAM:

VLSI LAB MANUAL

TRUTH TABLE:

2 Bit Counter

Clock Clear Output[2]

0 0 00

1 0 00

0 0 00

1 0 00

0 0 00

1 0 00

0 0 00

1 0 00

0 0 00

1 0 00

0 1 00

1 1 01

0 1 01

1 1 10

0 1 10

1 1 11

0 1 11

1 1 00

0 1 00

1 1 01

0 1 01

1 1 10

0 1 10

1 1 11

0 1 11

VLSI LAB MANUAL

SIMULATED WAVEFORM:

RESULT:

VLSI LAB MANUAL

Expt No: STUDY OF SYNTHESIS TOOLS

Date:

AIM:

To study the synthesis tool.

THEORY:

Now that you have created the source files, verified the design behavior

with simulation, and added constraints, you are ready to synthesize and

implement the design.

Implementing the Design:

1. Select the counter source file in the Sources in Project window.

2. In the Processes for Source window, click the “+” sign next to

Implement Design. The Translate, Map, and Place & Route processes are

displayed. Expand those processes as well by clicking on the “+” sign. You

can see that there are many sub-processes and options that can be run

during design implementation.

3. Double-click the top level Implement Design process.ISE determines

the current state of your design and runs the processes needed to pull your

design through implementation. In this case, ISE runs the Translate, Map

and PAR processes. Your design is now pulled through to a placed-and-

routed state. This feature is called the “pull through model.”

4. After the processes have finished running, notice the status markers in

the Processes for Source window. You should see green checkmarks next to

several of the processes, indicating that they ran successfully. If there are

any yellow exclamation points, check the warnings in the Console tab or

the Warnings tab within the Transcript window. If a red X appears next to a

process, you must locate and fix the error before you can continue.

VLSI LAB MANUAL

Figure 7: Floor planner View - Detailed View

Figure 8: Design Summary View

VLSI LAB MANUAL

Verification of Synthesis:

Your synthesized design can be viewed as a schematic in the Register

Transfer Level (RTL) Viewer. The schematic view shows gates and

elements independent of the targeted Xilinx® device.

1. In the Processes for Source window, double-click View RTL

Schematic found in the Synthesize - XST process group. The top

level schematic representation of your synthesized design opens in

the workspace.

2. Right-click on the symbol and select Push Into the Selected

Instance to view the schematic in detail. The Design tab appears in

the Sources in Project window, enabling you to view the design

hierarchy. In the schematic, you can see the design components you

created in the HDL source, and you can “push into” symbols to

view increasing levels of detail.

3. Close the schematic window.

RESULT:

VLSI LAB MANUAL

Expt. No: STUDY OF PLACE AND ROUTE AND BACK

ANNOTATION FOR FPGA

Date:

AIM:

To study the Place and Route and Back annotation for FPGAs.

THEORY:

After implementation is complete, you can verify your design before

downloading it to a device.

Viewing Placement:

In this section, you will use the Floor planner to verify your pin outs and

placement. Floor planner is also very useful for creating area groups for

designs.

1. Select the counter source file in the Sources in Project window.

2. Click the “+” sign to expand the Place & Route group of processes.

3. Double-click the View/Edit Placed Design (Floor planner) process.

The Floor planner view opens.

4. Select View _ Zoom _ ToBox and then use the mouse to draw a box

around the counter instance, shown in green on the right side of the

chip.

5. This Fig 8 shows where the entire design was placed. Click on any of

the components listed in the Design Hierarchy window to see where each

component is placed.

6. Zoom in to the right side of the chip even more, and place your mouse

over the K13pad. You can see that your pinout constraint was applied -

the DIRECTION pin is placed at K13.

VLSI LAB MANUAL

7. Close the Floor planner without saving.

Viewing Resource Utilization in Reports:

Many ISE processes produce summary reports which enable you to check

information about your design after each process is run. Detailed reports are

available from the Processes for Source window. You can also view summary

information and access most often-utilized reports in the Design Summary.

1. Click on the Design Summary tab at the bottom of the window. If

you closed the summary during this tutorial, you can reopen it by double-

clicking the View Design Summary process.

Figure 9: Timing Analyzer - Timing Summary

2. In the Device Utilization Summary section, observe the number of

Slice Flip Flops that were used during implementation. You should see 4 flip

flops, since you implemented a 4-bit counter.

3. To see other reports, scroll to the bottom of the Design Summary. You

can click on a report from here to view it in the ISE Text Editor.

VLSI LAB MANUAL

Figure 10: FPGA Editor - Detailed View

Timing Closure:

In this section, you will run timing analysis on your design to verify that

your timing constraints were met. Timing closure is the process of working on

your design to ensure that it meets your necessary timing requirements. ISE

provides several tools to assist with timing closure.

1. In the Processes for Source window, under the Place & Route group

of processes, expand the Generate Post-Place & Route Static Timing group

by clicking the “+”sign.

2. Double-click the Analyze Post-Place & Route Static Timing

process. The Timing Analyzer opens.

3. To analyze the design, select Analyze Against Timing Constraints.

The Analyze with Timing Constraints dialog box opens.

VLSI LAB MANUAL

4. Click OK. When analysis is complete, the timing report opens.

5. Select Timing summary from the Timing Report Description tree in

the left window. This displays the summary section of the timing report, where

you can see that no timing errors were reported.

Close the Timing Analyzer without saving.

Viewing the Placed and Routed Design:

In this section, you will use the FPGA Editor to view the design.

You can view your design on the FPGA device, as well as edit the placement

and routing with the FPGA Editor.

1. Double-click the View/Edit Routed Design (FPGA Editor) process

found in the Place & Route group of processes. Your implemented design opens

in the FPGA Editor.

2. Look in the List window to examine your design components.

3. Click on the COUNT_OUT K12 IOB in the List window to select the

row. This is one of the outputs in your design.

4. With the COUNT_OUT K12 row selected, select View _ Zoom

Selection. In the editor window, you can see the COUNT_OUT<0> IOB

highlighted in red.

5. Push into (double-click) the red-highlighted COUNT_OUT K12

IOB. You should see Fig 10.

6. Enlarge the window and zoom in so you can see more detail. This

view shows the inside of an FPGA at the lowest viewable level. The blue line

shows the route that is used through the IOB. The red lines show the routes that

are available.

7. Verify that the signal goes to the pad as an output.

8. Close the FPGA Editor.

VLSI LAB MANUAL

Figure 11: Simulator Processes for Test Bench

Figure 12: Timing Simulation in ISE Simulator

VLSI LAB MANUAL

Timing Simulation (ISE Simulator):

You can verify that your design meets your timing requirements by running

a timing simulation. You can use the same test bench waveform that was used

earlier in the design flow for behavioral simulation. When running timing

simulation, the ISE tools create a structural HDL file which includes timing

information available after Place and Route is run. The simulator will run on a

model that is created based on the design to be downloaded to the FPGA.

If you are using ISE Base or Foundation, you can simulate your design

with the ISE Simulator. To simulate your design with ModelSim, skip to the

“Timing Simulation (ModelSim)” section.

To run the integrated simulation processes:

1. Select the test bench waveform in the Sources in Project window. You

can see the ISE Simulator processes in the Processes for Source window.

2. Double-click the Simulate Post-Place & Route Model process.

This process generates a timing-annotated net list from the implemented

design and simulates it. The resulting simulation is displayed in the Waveform

Viewer. These results look different than those you saw in the behavioral

simulation earlier in this tutorial. These results show timing delays.

3. To see your simulation results, zoom in on the transitions and view the

area between 300 ns and 900 ns to verify that the counter is counting up and

down as directed by the stimulus on the DIRECTION port.

4. Zoom in again to see the timing delay between a rising clock edge and

an output transition.

5. Click the Measure Marker button and then click near the 300 ns

mark. Drag the second marker to the point where the output becomes stable

to see the time delay between the clock edge and the transition.

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6. Close the waveform view window. You have completed timing

simulation of your design using the ISE Simulator. Skip past the ModelSim

section below, and proceed to the “Creating Configuration Data” section.

Timing Simulation (ModelSim):

If you have a ModelSim simulator installed, you can simulate your design

using the integrated ModelSim flow. You can run processes from within ISE

which launches the installed ModelSim simulator.

1. To run the integrated simulation processes, select the test bench in the

Sources in Project window. You can see the ModelSim Simulator processes in

the Processes for Source window.

Figure 13: Simulator Processes for Test Bench

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Figure 14: Timing Simulation in ModelSim

2. Double-click the Simulate Post-Place & Route VHDL/Verilog

Model process.



DIRECTION port.

4. Zoom in on the rising clock edges to see that the output transitions

occur slightly later due to the timing delay.

5. Close the ModelSim window.

RESULT:

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Expt. No: CMOS INVERTER

Date:

AIM:

To perform the functional verification of the CMOS Inverter through

schematic entry.

APPARATUS REQUIRED:

S-Edit using Tanner Tool.

THEORY:

CMOS Inverter consists of nMOS and pMOS transistor in series

connected between VDD and GND. The gate of the two transistors are shorted

and connected to the input. When the input to the inverter A = 0, nMOS

transistor is OFF and pMOS transistor is ON. The output is pull-up to VDD.

When the input A = 1, nMOS transistor is ON and pMOS transistor is OFF. The

Output is Pull-down to GND.

PROCEDURE

1) Draw the schematic of CMOS Inverter using S-edit.

2) Perform Transient Analysis of the CMOS Inverter.

3) Obtain the output waveform from W-edit.

4) Obtain the spice code using T-edit.

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SCHEMATIC DIAGRAM:

SIMULATED WAVEFORM:

RESULT:

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Expt. No: UNIVERSAL GATES

Date:

AIM:

To perform the functional verification of the universal gate through

schematic entry.

APPARATUS REQUIRED:


PROCEDURE





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NAND GATE

SCHEMATIC DIAGRAM:

SIMULATED WAVEFORM:

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NORGATE SCHEMATIC DIAGRAM

SIMULATED WAVEFORM:

RESULT:

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Expt. No: DIFFERENTIAL AMPLIFIER

Date:

AIM:

To calculate the gain, bandwidth and CMRR of a differential amplifier through schematic entry. APPARATUS REQUIRED:


Theory:

A differential amplifier is a type of electronic amplifier that multiplies

the difference between two inputs by some constant factor (the differential gain).

Many electronic devices use differential amplifiers internally. The output of an

ideal differential amplifier is given by:

Where Vin+ and Vin- are the input voltages and Ac is the differential gain.

In practice, however, the gain is not quite equal for the two inputs. This means

that if Vin+ and Vin- are equal, the output will not be zero, as it would be in the

ideal case. A more realistic expression for the output of a differential amplifier

thus includes a second term.

Ac is called the common-mode gain of the amplifier. As differential

amplifiers are often used when it is desired to null out noise or bias-voltages that

appear at both inputs, a low common-mode gain is usually considered good.

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The common-mode rejection ratio, usually defined as the ratio between

differential-mode gain and common-mode gain, indicates the ability of the

amplifier to accurately cancel voltages that are common to both inputs.

Common-mode rejection ratio (CMRR):

PROCEDURE:

1. Draw the schematic of differential amplifier using S-edit and generate the

symbol.

2. Draw the schematic of differential amplifier circuit using the generated

symbol.

3. Perform AC Analysis of the differential amplifier.

4. Obtain the frequency response from W-edit.

5. Obtain the spice code using T-edit.

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SCHEMATIC DIAGRAM:

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SIMULATED WAVEFORM:

RESULT:

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Expt. No: LAYOUT OF CMOS INVERTER

Date:

AIM:

To draw the layout of CMOS Inverter using L-Edit and extract the SPICE

code.

APPARATUS REQUIRED:

L-Edit & T-SPICE - Tanner Tool.

PROCEDURE

1. Draw the CMOS Inverter layout by obeying the Lamda Rules using L-

edit.

i. Poly - 2λ

ii. Active contact - 2 λ

iii. Active Contact – Metal - 1 λ

iv. Active Contact – Active region - 2 λ

v. Active Region – Pselect - 3 λ

vi. Pselect – nWell - 3λ

2. Check DRC to verify whether any region violate the lamda rule.

3. Setup the extraction and extract the spice code using T-spice.

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CMOS INVERTER:

SIMULATED WAVEFORM:

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LAYOUT DIAGRAM:

RESULT:

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Expt. No: DESIGN OF A 10 BIT NUMBER CONTROLLED

OSCILLATOR

Date:

AIM:

To perform the functional verification of the design of a 10 bit number

controlled oscillator through schematic entry.

APPARATUS REQUIRED:


PROCEDURE





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SCHEMATIC DIAGRAM:

SIMULATED WAVEFORM:

RESULT:

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Expt. No: AUTOMATIC LAYOUT GENERATION

Date:

AIM:

To generate the Layout from the schematic using the Tanner tool and verify

the layout using simulation.

APPARATUS REQUIRED:

S-Edit, L-Edit using Tanner Tool.

Conversion procedure for schematic to Auto layout

Step1: Draw the schematic using S Edit and verify the output in W Edit.

Step2: Extract the schematic and store it in another location

Step3: Open the L Edit, open the design in Ring VCO

Step4: Create the new cell.

Step5. Open the schematic file (.sdl) using the SDL Navigator

Step6: Do the necessary connections as per the design.

Step7: Name the ports and check the design for the DRC Rules

Step8: Locate the Destination file in the setup Extract window and extract

the layout.

Step9: Include the Library and the print voltage statements in the net list

which is obtained.

Step10: Verify the layout design using W Edit.

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SCHEMATIC DIAGRAM:

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LAYOUT:

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SIMULATED WAVEFORM:

RESULT:

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APPENDIX

How to work in XILINX

Step 1: Open Xilinx software

Step 2: Select File New Project

Step 3: In the New Project window enter project name and project location

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Step 4: Select the corresponding entries for the property names

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Step 5: Click New Source. Step 6: Enter the file name and then select Verilog module.

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Step 7: Define the input and output port names, then click Next for all

successive windows.

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Step 8: The Verilog file will be created under .ise file.

Step 9: Double click the Verilog file and enter the logic details and save the

file.

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Step 10: Double click Synthesize – XST for checking the syntax.

Step 11: Right click the halfadd.v file and select new source, then click

Implementation Constraints File and enter the filename.

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Step 12:.ucf file will be created.

Step13: Open the .ucf file and enter the pin location and save the file.

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Step14: Go to Generate programming file and select Generate PROM, ACE or

JTAG file in the processes window.

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Step 15: In Slave Serial mode, right click and select Add Xilinx Device.

Step 16: In the Add Device window select the .bit file to add the device.

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Step 17: Connect the RS232 cable between computer and kit. Connect the SMPS

to kit and switch on the kit.

Step 18: Right click the device and select Program to transfer the file to kit.

Step 19: After successful transmission of file “Programming Succeeded” will be

displayed.

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vlsi manual

Documents

design entry

study of simulation

vlsi lab manual contents

vlsi lab manual fig

post pr simulation

design gate count

basics of ic design

study of synthesis tools