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- Homework Statement
- Does the following simple test deduced from Nyquist criterion also apply to positive feedback or it needs to be modified?

- Relevant Equations
- If magnitude of loop gain i.e. |T (jω)| > 1 at the frequency where phase(T (jω))= −180◦, then the amplifier is unstable.

Does the following simple test deduced from Nyquist criterion also apply to positive feedback or it needs to be modified?

If magnitude of loop gain i.e. |T (jω)| > 1 at the frequency where phase(T (jω))= −180◦, then the amplifier is unstable.

Reference:

Analysis and Design of Analog Integrated Circuits, 5th Edition http://fa.ee.sut.ac.ir/Downloads/Ac...sign_of_Analog_Integrated_Circuits_5th_ed.pdf, pg 628 2nd last paragraph

https://www.allaboutcircuits.com/te...ve-feedback-part-4-introduction-to-stability/

If magnitude of loop gain i.e. |T (jω)| > 1 at the frequency where phase(T (jω))= −180◦, then the amplifier is unstable.

Reference:

Analysis and Design of Analog Integrated Circuits, 5th Edition http://fa.ee.sut.ac.ir/Downloads/Ac...sign_of_Analog_Integrated_Circuits_5th_ed.pdf, pg 628 2nd last paragraph

https://www.allaboutcircuits.com/te...ve-feedback-part-4-introduction-to-stability/