problems about CMFB of a full-differential two-stage OPA

[nksunmoon]

Hi guys, I want to design a full-differential two-stage OPA. The first stage is telescope cascode structure and the second on is usual common source structure. I want to use switched-capacitor CMFB to make the output common-mode voltage stable.
I am wondering now that how many SC-CMFBs I should add in the OPA. One SC-CMFB only for the second stage or two SC-CMFBs for each stages? Is there anyone who has the experience about this issue? I really need some help and appreciate your suggestions.

 

[petitidiot]

Have you got the answer? If not, please refer to this link: https://www.edaboard.com/threads/60415/