bababui
Junior Member level 3
Opamp Stability
Hello,
When looking at the frequency response of an opamp, I have learned that opamp is considered to be stable if at the frequency where it has unity gain, 180-phase=positive number. In my textbook, bode plot of an opamp has phase starting off at 0 degrees at low frequencies and shifting down. However, in the opamp that I built, phase starts at 180 degrees and starts going down, and it's total phase shift by frequency where it has unity gain is around 240degrees.
My question is, should the phase start off at 0? Am I correct to measure stability in terms of total phase shift?
Thanks
Hello,
When looking at the frequency response of an opamp, I have learned that opamp is considered to be stable if at the frequency where it has unity gain, 180-phase=positive number. In my textbook, bode plot of an opamp has phase starting off at 0 degrees at low frequencies and shifting down. However, in the opamp that I built, phase starts at 180 degrees and starts going down, and it's total phase shift by frequency where it has unity gain is around 240degrees.
My question is, should the phase start off at 0? Am I correct to measure stability in terms of total phase shift?
Thanks