Hello, Can someone please help me to understand how should I stablize following feedback loop?


                             Sine Wave
                                 |
--Diff Amp----Error Amp ------Power Amp----Load
|                                                                                |
|                                                                                |
-------------------------------------------------------
As it has been drawn, a sine wave is fed to an error amp and the output of error amp is fed via a power amplifier to a load. An instrument differential amplifier then reads the voltage across the load and it is fed back to error amp to keep voltage stable.
The problem is due to phase shift of diff amp and power amp there will be instability in this loop. I can compensate via an RC network over error amp to provide alternative feedback path but as amount of alternative feedback increases, sensetivity of error amp decreases. In searching for answer, I read that I should limit the bandwidth of power amplifier but how? does that mean that I have to place LPF between error amp and power amp but it increases phase shift. so how should I limit the bandwidhth of power amplifier to stablize the loop?
Thank you.

Regards.