Help with CMOS Op Amp Design in SPICE

[jdyrholm]

cmos op amp design

I have a question concerning the design of CMOS Op Amp in Spice. My professor gave us this project 2 weeks before the end of the semester, and I am stressed with this and studying.

Anywho....how should I begin with the following specs:

VDD = -Vss = 3.00 V
Av > 5000
Phase Margin = 40-60-degrees
Unity Gain Bandwidth > 5 MHz
SR > 10 V/micro-s for a CL of 10 pF
-1.0 V ≤ Input Common Mode Range ≤2.0 V
Output Voltage Range of ±1.7 V
Number of active devices <18
Total resistors value not to exceed 100kΩ
Channel length of all devices = 0.8 micro

It has to be simulated with Spice

Thanks!

 

[Ahmed Ragab]

cmos op amp spice model

I guess you should start with circuits that might be similar to the one you need to design, I mean basic differential amplifier circuits using Mosfets

Try to start with an already made design and understand how the simulation should be done, then you'll be able of modifying the design to meet the specs mentioned by your professor.

 

[pfd001]

I think that two sage opamp will be easy to satify your spec. There are a lot of materials in razavi and other analog design books

 

[hehongyu2001]

reference:
cmos analog circiut design,second edition.
P.E.Allen

you can get the examples you need.

 

[liuhongflyfly]

something also related it in Razavi's chap 9

 

[Chethan]

Steps u can follow to design an amplifier:

1) Decide with the architecture of the opamp which meets your specifications. Like Single stage opamp, two stage, Folded cascode etc.

2) Determine the type of compensation needed for your specifications. This depends on how many stages your opamp has.

3) Hand calculate the current, voltages etc according to your specifications and then size your transistors. For eg, if you know your slew rate and output cap from specs then you can decide upon your current.

4) Run simulations for variety of test cases to determine PSRR,ICMR, Slewrate, BW etc.


In your specifications, I think you can decide upon a two stage OPAMP with PMOS input diff amp(coz of the ICMR range). Also as your gain is high, u can go for a second stage(CS stage).But, I dont know whether your CS stage can give u an output voltage swing of 1.7V. As far as your compensation, I think a NMC compensation will do.

 

[SANJAY.MADUPU]

how to calculate sr of amplifier

 

[tuza2000]

1.hand calculate
2.two stage with miller compensarion
3.not start wit spice but calculate