VLSI Techniques-ELEC 30007 –SPRING-2018 – CW1–QP

This document contains solutions for VLSI Techniques-ELEC 30007 –SPRING-2018 – CW1–QP. It includes calculation of resistance of polysilicon wire, design of half adder circuit using CMOS transistors, drawing stick diagram of half-adder circuit and determining optimum operation of the circuit.

VLSI Techniques-ELEC 30007 –SPRING-2018 – CW1–QP
1. Calculate the resistance of the polysilicon wire as shown in following figure. The polysilicon wire
is fabricated using 1μm technology. Given RS=6 ohm/square.
Figure 1: Polysilicon wire
Solution:
R= Rs∗l
w
Rs=6 w=3 λ=1 μM l=49 λ=16.333 μM
Therefore:
ELEC 30007 (QP) Page 1 of 7
Assignment - SPRING 2018
Module: VLSI Techniques (ELEC 30007) ID NUMBER
Level: 3 Max. Marks: 100

VLSI Techniques-ELEC 30007 –SPRING-2018 – CW1–QP
R=6∗49
3∗1 =98 Ω
Resistance of the polysilicon wire=98 Ω
2. Design of a Half adder circuit using CMOS transistors:
a. Realize the Half adder circuit using static CMOS transistor.
Solution:
Truth Table of 1-Bit Half Adder:
INPUTS OUTPUTS
A B S C
0 0 0 0
0 1 1 0
1 0 1 0
1 1 0 1
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VLSI Techniques-ELEC 30007 –SPRING-2018 – CW1–QP
Circuit Realisation:
Figure 2: Half adder circuit realization in multisim
ELEC 30007 (QP) Page 3 of 7

VLSI Techniques-ELEC 30007 –SPRING-2018 – CW1–QP
b. Draw the stick diagram of Half-adder circuit.
Solution:
Figure 3: Stick diagram of Half-adder circuit
c. Appropriate device sizing can result in equal and symmetrical drive current which leads to a
sustainable design. In order to obtain optimum operation of the circuit determine the ( W
L )p , eq
and ( W
L )n , eq
for the half adder circuit. Assume that ( W
L )p
=30 for all PMOS transistors and
( W
L )n
=15 for all NMOS transistors.
Solution:
Total PMOS transistors=8
Total NMOS transistors=8
Series:
( W
L ) EQ
= 1
( W
L )1
+ ( W
L )2
+… .
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VLSI Techniques-ELEC 30007 –SPRING-2018 – CW1–QP
Parallel:
( W
L )EQ
= ( W
L )1
+( W
L )2
+…
( W
L )p , eq
=30∗3+ 1
30∗3 + 1
2∗30 =90.0278
( W
L )n , eq
= 2
15∗2 +15∗4=60.067
ELEC 30007 (QP) Page 5 of 7

VLSI Techniques-ELEC 30007 –SPRING-2018 – CW1–QP
Reference
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VLSI Techniques-ELEC 30007 –SPRING-2018 – CW1–QP
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