How to guarantee the stability of a RF closed loop amplifier with inner loops?
In many cases, the inner loops have smaller time constants (reaction time) and the stability properties of the whole circuit (closed-loop) are determind primarily by the outer (overall) loop which is the slowest one.
When you cannot open the inner loops you have to live with this situation....unless the circuit is unstable when the outer main loop is open. In this case, you must use the complete Nyquist criterion for the special case &quot;unstable loop gain&quot; for finding some methods to stabilize the closed loop.
With other words: Treat the closed-loop circuit as it would have no inner loops.