Free Gain Margin Calculator
Calculate the gain margin from the open-loop gain at the phase crossover frequency for stability assessment.
Gain Margin (absolute)
2.000
Gain Margin (absolute) vs Open-Loop Gain at Phase = -180° (|G|)
Gain Margin
Gain margin measures how much the open-loop gain can increase before the system becomes unstable. It is evaluated at the phase crossover frequency (where the open-loop phase equals -180°).
Formula
GM = 1 / G(j*omega_pc) = -20*log10( G(j*omega_pc)
where omega_pc is the phase crossover frequency. A positive gain margin (in dB) indicates stability. The larger the gain margin, the more robust the system is to gain variations.
Example Calculation
The open-loop gain magnitude at -180° phase is 0.5.
- 01GM = 1 / 0.5 = 2.0 (absolute)
- 02GM = -20 × log10(0.5) = -20 × (-0.301) = 6.02 dB
- 03The gain can be increased by 100% before instability
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