Two stage amplifier with large load capacitance

[deveshkm]

For 68 dB gain and load cap = 40 nF ,
First stage is folded cascode
For second stage , should I design class AB amplifier?

 

[FvM]

Re: Two stage with large load capacitance

Depends on the intended bandwidth and signal magnitude, which aren't mentioned, unfortunately.

 

[deveshkm]

Input swing 10m
Unity gain frequency 75kHz

 

[frankrose]

Do you have a current consumption limit? You can use class A output stage if consumption is arbitrary, and the output slew-rate is not very high.

 

[deveshkm]

Current limit 200uA.
Slew rate 2 V/ms
I don't understand power amplifier using MOS

 

[frankrose]

With this slew-rate I think you can use a normal class-A output stage.
You will need 80uA at the output with 40nF. So you will have enough spare current for the 1st stage, the bias and even for the output stage.
Another important thing before you start is the output swing or headroom. Class-A output will definitely limit the lower or higher maximum output voltage, but some class-AB structure can limit these values more.