General question. I see a lot of two stage amplifiers with a diff pair input and a cs second stage. In IC design these two stages are always directly coupled ie. the dc bias of the second stage is fed directly from the output of the first.
The question is then how does one properly bias the second stage? The usual method of having a current mirror acting as a current source works great at typical; however over PVT either the CS fet or the mirror fet will go into the triode region.
I see it as a two high impedance sources fighting each other. Is there a way to get around this?
Edit: For instance M8 and M7. M8 is the input device to the second stage and M7 is the mirror biased transistor.