I am aware of the scenario where an isolation resistor is used to decouple a capacitive load from an opamp. If you then want to take feedback from after the isolation resistor you will be taking feedback from a location that is low pass filtered (because of the capacitive load combined with the isolation resistor). Stability is maintained by placing a small cap between the opamp output and the inverting input to provide a high frequency feedback path.
This is great, but what do you do if you want to take feedback from a location that is bandpass filtered? For instance if you used an opamp to drive a transformer, and you wanted to take the feedback after the transformer to account for the non-linearity of it. I understand this isn't really a perfect example, since transformers can have a fairly wide bandwidth. But still, the situation must come up...
Do you just provide a low frequency and high frequency feedback path directly from the opamp output (i.e. a cap and an inductor). Do the three feedback paths then have to be coupled to one another? What if you want to limit the inductive loading?
Thanks,
Jay