Btrend thanks for your reply
My OTA is stable with a phase margin of 86 degrees.
My CMFB is unstable because its has a phase margin of -20 degrees, I am getting some ripples before the output common mode voltage settles to its desired value.
One way can be to decrease the gain of the CMFB , but it may not be a good solution. Is there some compensation that I can do to stabilize it?
If you can also point out to some links that discuss the stability of switched CMFB , it will be of great help