need help in designing opamp

[avlsi]

design steps for op amp

Suppose , I have only the specificatin of DC open loop gain and Common mode gain and ICMR and OCMR.

How will I proceed to design the opamp. I need a high gain opamp,so I chose Miller opamp. But I would like to know,how will we decide the currents.(no slew rate is given).

 

[caosl]

I think you should know more specifications to optimize you design.Only DC gain is not enough.

 

[avlsi]

Suppose I know that my gain is around 90 dB and fu is 1 M Hz. How will we decide the currents. Share some methodology.

Can we do anything with ICMR and OCMR.

Thanks in advance.

 

[shaikhsarfraz]

Hi,
For most of the design of Op Amp we have the slew rate, the supply voltage, Load capacitance, CMRR, Gain, Fu.
Based on these value we find the transistor sizes so that all the specifications are met.
I donnot think that without slew rate and load capacitance you can get the Current.
You can do one thing that you can assume some value for Slew rate and then proceed so that all your specs are met, then optimise for the best solution.

Go through the book by Allen Hollberg. He has given proper design steps for designing Op Amp

Thanks
Shaikh Sarfraz