I have designed a two stage opamp for use in switched capacitor applications.
I want to use Switched Cap CMFB for it - I only need the CMFB for the one stage of the opamp - is this correct - the bias voltage of the current mirror.
See attached picture - vbias in picture is vcontrol is the SC CFMB circuit and vbias of the opamp is vbias of the SC CMFB.
Is this correct ?
The "second" stage does not need a CMFB circuit - is this correct ?
The CMFB used to give a separate DC CM gain at the output. Here you are sensing second stage output (which is indeed the "main" output) and regulating "any" internal bias node on a negative feedback. That's why the CMFB is applied for the whole circuit, don't need to think about the stages individually.