This document describes the design and characterization of a two-stage operational amplifier (op-amp) using MOS transistors in Cadence. It first details the design of the op-amp circuit and then discusses calculations for its power dissipation, delay, bandwidth, frequency, and gain-bandwidth product using the Cadence tool. The power dissipation is broken down into average, static, and dynamic components. Each characterization metric is calculated using the Cadence Analog Design Environment and the results analyzer.

1. 0
Design a Two-Stage Operational
Amplifier using MOS Transistors and
find its different characteristics using
Cadence tool
Submitted to
Ms. Dipti Gridhar
Submitted by
Rajesh Yadav
12ECP01P
M.Tech (VLSI – Design)

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INDEX
1. Two-Stage Operational Amplifier Design………………………………..
Introduction
Design
02
02
02
2. Characterization of OPAM………………………………………………
1. Power dissipation Calculation
Average Power
Static Power
Dynamic Power
2. Delay Calculation ……………………………………………
3. Bandwidth calculation……………………………………….
4. Frequency Calculation……………………………………….
5. Gain-Bandwidth Product Calculation……………………….
03
03
02
10
12
13
15
16
17

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Chap.1 Two-stage Operational Amplifier Design
Introduction
CMOS Op-Amps are ubiquitous integral parts in various analog and mixed-signal circuits. The
term OTA was originally conceived for operational transconductance amplifiers with linear
transconductance (used for the implementation of continuous-time filters), for the sake of simplicity we
will use the same term OTA for general operational trans conductance amplifiers. The two-stage Op-
Amp is widely used because of its simple structure and robustness.
Design:
Draw the schematic of a differential operational amplifier and apply the Vdd , Vss
and Vbias, as shown in figure in Cadence Virtuoso.

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Chap : 2 Characterization of OPAM
1. Power dissipation calculation
A. Average power:
Steps:
1. Draw the circuit and save without any error.
2. Launch ADE L (Launch -> ADE L)
3. Go to Setup and set stimuli.

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4. Go to Analysis and choose trans Analysis, set stop time (say 100ms) and tick
for moderate, do apply and ok
5. Go to Output ->Save All, Tick all to Selected signals to output, select power
signal to output and select device current.

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6. Go to output -> To Be ploted -> Select On Schematic, select the signals whose
graph have to plot, and return to Analog Design Environment Window and tick
to save for all signals
7. To Run, go to Simulation -> Netlist and Run. OR simply click on Run Button.
8. All the selected signal will be ploted on Visualization and analysis XL window

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9. Go to Browser -> Result ->Open results and click on psf
10. Open tran folder under signal tab of visualization and analysis XL
11.Select :pwr, A power signal will be added on visualization and analysis XL
window, select power signal

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12. Click on Calculator
13. A Visualization and analysis XL Calculator will be open, close Stack

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14. Set all in function panel and click on average.
15.Corresponding command on calculator display will be as shown in bellow:
16. Click on the button “Evaluate the buffer. If scalar display in buffer. If
waveform, plot”.

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17.The average power will be calculated and result will be as shown as bellow.
18.End.

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B. Static power:
Steps
1. Disable the all actuating signal acting on the circuit, except Vdd, Vbias and
Vss, from setup analog stimuli. (setup -> stimuli)
2. Click on Netlist and run
3. Go to Browser -> Result -> Open Results, select psf

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4. Follow the step-10 to step-17 of the procedure of average power calculation.
5. End

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C. Dynamic Power
Steps
1. Average power = Static power + Dynamic power
Therefore, Dynamic power = Average Power – Static Power.
2. We have calculated Average power and Static power, so just substitute these
values in the expression of step 1 and calculate dynamic power.
Results: Average power= 633 E-03 watt
Static Power = 629 E-03 watt
S0 Dynamic Power = (633E-03) – (629E-03) = 4E-03 Watt

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2. Delay calculation
Steps
1. Follow the same steps up to step 14 of average power calculation.
2. Select delay from function panel of calculator.
3. Set the parameters (signal 1 and signal 2) as you wish or may refer figure
bellow.
4. Do Apply and then Ok.
5. click on evaluate

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6. Result (Delay) will be displayed on calculator output screen.
7. End

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3. Bandwidth Calculation
Steps
1. Follow the same steps up to step 14 of average power calculation.
2. Select Bandwidth from function panel of calculator.
3. Select the signal from drop down list-> select vout
4. Set db = 3 type = high
5. Do Apply and Ok, click on evaluate
6. Result (Bandwidth) will be displayed on calculator output screen.
7. End

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4. Frequency Calculation
Steps
1. Follow the same steps up to step 14 of average power calculation.
2. Select Frequency from function panel of calculator.
3. Corresponding command on display will be as shown in figure bellow.
4. click on evaluate, corresponding Result (Frequency) will be displayed on the
output of Calculator.
5. End

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5. Gain-Bandwidth Product Calculation
Steps
1. Follow the same steps up to step 14 of average power calculation.
2. Select Gain-Bandwidth Product from function panel of calculator.
3. Corresponding commands on the display of calculator will be as shown in the
figure.
4. click on evaluate, corresponding Result (Gain-Bandwidth Product) will be
displayed on the output of Calculator.
5. End