greenjuice
Member level 1

As my attached picture, if we have negative feedback system, we should make unity gain be within -180 phase not to oscillate our system, considering the number of pole in amp.
And I think,
upper unity gain frequency, my Aol(in the picture) already has -180 phase because amp has negative gain. so without considering the number of pole in amp, -180 by gain + -180 by negative feedback.. = -360 phase so. my system could osciilate.
But in real, amp has several pole. so it is not oscillate.
Is my view right? I'm so confused.
Plus, why does amp have -90 phase at the pole?

And I think,
upper unity gain frequency, my Aol(in the picture) already has -180 phase because amp has negative gain. so without considering the number of pole in amp, -180 by gain + -180 by negative feedback.. = -360 phase so. my system could osciilate.
But in real, amp has several pole. so it is not oscillate.
Is my view right? I'm so confused.
Plus, why does amp have -90 phase at the pole?
