n-bit comparator layout design

VLSI Project4 bit Comparator

Submitted To

Fariah HayeeLecturer,

Faculty of EEE,BUET

Maruf AhmedLecturer,

Faculty of EEE,BUET

Submitted By

Ashik Amin Mohammad Wahiduzzaman Khan

Std ID #0806098 Std ID #0806144

Group 27

Outline

• Specification, Architectural Design and Functional Verification

• Gate Level Schematic Design• Transistor Level Design and Cell Layout• Layout Placement and Routing• Layout of Full Chip, DRC & LVS Log

Characteristic of a Comparator

Input Output

Ai Bi Di+1 Ci+1 Ci Di

x x 1 0 1 0

x x 0 1 0 1

0 0 0 0 0 0

0 1 0 0 0 1

1 0 0 0 1 0

1 1 0 0 0 0

X signifies “don’t care”

Schematic

This type of cascade-able connection lessens the number of not gates reqd (2 for each block). Thus reducing the area of layout

significantly.COMPCELLA COMPCELLBInverted I/P True I/P

True O/P Inverted O/P

Waveform

A B Cout

Dout

4 4 0 02 4 0 12 1 1 07 1 1 0

RTL

Gates’ Schematic and Layout

CompcellA

CompcellB

Comparator

IO Pad

Simulation (ADE L)

Delay 50.8497-50.75=0.0997ns

Average Power 1.324E-6