can anyone tell me when SC CMFB is used in a fully differential amplifier, what is the best ratio between the CMFB bandwidth and differential bandwidth? thank you
Many papers describe this problem.Some said the BW of CM should as large as the DM path.Some said CM BW can be smaller than the DM path.Some time,it's difficult to design a large BW for CM path unless using some special tech like CMFF.
You can search these papers and you can find the suitable one for your design.