loop gain

[Lucky-Luka]

Hi all
In the last few days I've tried to understand how to get loop gain of my amplifier circuit.
I've received several suggestion.
I would like to hear your opinion on this matter.
Are these 2 methods equivalent? Are they correct?
Cheers

 

[audioguru]

You show a huge inductor and huge capacitor in the negative feedback parts I guess to provide DC negative feedback but block AC negative feedback?
Then you can measure the open-loop gain.

When you connect the negative feedback to measure the closed-loop gain then the phase shift is high and without frequency compensation with some Miller capacitance then the amplifier will be unstable with transients (high frequency ringing) or oscillation.