What is gain margin in bode plot

The gain margin in dB is the amount of open loop gain at 180 degrees phase shift to make the closed loop system unstable. It is the difference in gain between 0 dB and the measured gain where the phase crosses 180 degrees.

1. What is the gain margin?
2. What is gain margin and phase margin in Bode plot?
3. What does high gain margin mean?
4. What is a good gain and phase margin?

What is the gain margin?

Gain margin is defined as the amount of change in open-loop gain needed to make a closed-loop system unstable. The gain margin is the difference between 0 dB and the gain at the phase cross-over frequency that gives a phase of −180°.

What is gain margin and phase margin in Bode plot?

In other words, the gain margin is 1/g if g is the gain at the –180° phase frequency. Similarly, the phase margin is the difference between the phase of the response and –180° when the loop gain is 1.0. The frequency Wcp at which the magnitude is 1.0 is called the unity-gain frequency or gain crossover frequency.

What does high gain margin mean?

More gain margin means more stability. Similarly, phase margin is the difference (expressed as a positive number) between 180° and the phase shift where |Aβ| crosses 0 dB.

What is a good gain and phase margin?

In general, the phase margin of 30–60 degrees and the gain margin of 2–10 dB are desirable in the closed-loop system design. A system with a large gain margin and phase margin is stable but has a sluggish response, while the one with a small gain margin and phase margin has a less sluggish response but is oscillatory.