This sounds like a problem with your circuit, not with
the chopper concept. I've seen recently a CSOA with
>100dB gain and <100uV Vio at test (not my design,
and not mine to divulge).
Chopper should operate out-of-band and moderate gain
and its per-cycle authority pretty small. Chopper only
works well when the input spends most of its time at
null, works poorly when forced to slew hard (fights itself
and accumulates bogus error-signal).
If by "readout circuits" you mean high pixel count ROICs
I think the chopper is a bad idea, video is not like the
usual DC/LV CSOA application (or if it was, why take a
picture at high frame rate?). You might want to take a
step back and consider other "autozero" techniques for
the front end pixel amplifier if that's what this is about.