Question on amplifier topology for 1.2V supply

[curious_engineer]

I am having trouble deciding the architecture for an amp to be used as an integrator for a sigma-delta ADC.

The supply is 1.2V. Does this rule out folded cascode? My idea was to make it one-stage in order to reduce the number of poles, but I don't know if its feasible w/ the limited supply. Maybe a typical miller compensated two stage (differential pair + CS) is better...

Also, with a high oversampling rate, wouldnt the clock frequency be so high that I would need to have this amp settle super fast in switched capacitor feedback configuration? That makes the design requirements fairly stringent I would think.

 

[JoannesPaulus]

Depending on the threshold voltage of your technology, it should not be too difficult to design a folded-cascode ota at 1.2V. I would at least try it since it will save you a lot of headaches with compensation.

Moreover, you can also scale the coefficients of the modulator according to the output swing (just one more degree of freedom).

In general, depending on your sampling rate, I would just be a little concerned about the bandwidth...