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| How can I obtain amplifier circuit loop gain? |
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| Lucky-Luka:
In the last few days I've tried to understand how to get the loop gain (Aol*ß) 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? The results look the same. Cheers |
| Benta:
"Loop gain" makes little sense. You can measure open-loop gain (x - x open) or closed-loop gain (x - x connected). Please clarify. |
| Lucky-Luka:
I have already said what it is... |
| Wimberleytech:
I typically use the inductor method. As an alternative do the test in two steps. First close the loop and get the node voltages at the input, then open the loop and drive those voltages into the inputs...yielding...hopefully...the same operating point. But to your question, I would say your two methods are mostly equivalent for ac analysis. |
| magic:
You have one of the sources backwards and phase is 180° off. The gigafarad capacitor always seemed intuitively right to me. The latter is weird, and who would want to edit the plots to divide by V(x) every time one switches to AC analysis. I don't like it. --- Quote from: Benta on January 16, 2020, 09:02:29 pm ---"Loop gain" makes little sense. You can measure open-loop gain (x - x open) or closed-loop gain (x - x connected). Please clarify. --- End quote --- There is even a wikipedia article on that ;) It makes sense. For example, unity loop gain frequency rather than unity gain frequency is the one you would care about in an amplifier permanently wired for high closed loop gain and decompensated correspondingly. Expect to see this jargon in anything related to audio amplifiers. |
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