What is Phase margin?
How far the phase lag is from 180° at the frequency where the feedback loop gain is 1 (0 dB). A small margin causes ringing, and zero or negative margin causes oscillation; 45-60° or more is a common target.
Phase margin in the explanations
As this is the deepest-feedback configuration, some op-amps lack phase margin and may oscillate, so check that the datasheet says "unity-gain stable."
Which correctly describes a voltage follower using an op-am…At frequencies where the phase shifts enough to make feedback positive, however, the loop oscillates, so phase margin must be secured.
What is the effect of applying negative feedback to an ampl…Phase margin is how far the loop's phase lag falls short of 180° at the frequency where loop gain equals 1 (0 dB).
Which metric is used to judge whether a negative-feedback a…
Questions that mention Phase margin (4)
- Which correctly describes a voltage follower using an op-amp?
- What is the effect of applying negative feedback to an amplifier?
- Which metric is used to judge whether a negative-feedback amplifier operates stably without oscillating?
- Which correctly describes the idea of dominant-pole compensation used in op-amps?
Related terms
Operational amplifier (op-amp) Voltage follower Negative feedback Miller effect Slew rate 1/f noise (flicker noise) Bandgap voltage reference CMRR (common-mode rejection ratio) Comparator Cutoff frequency