gain margin

gain margin

[′gān ‚mär·jən]
(control systems)
The reciprocal of the magnitude of the loop ratio at the phase crossover frequency, frequently expressed in decibels.
References in periodicals archive ?
The gain margin is the amount of gain increase or decrease required making the loop gain unity at the frequency where the phase angle is -180[degrees], and the phase margin is the difference between the phase of the response and -180[degrees] when the loop gain is 1.0.
On the other hand, the loop gain method [9, 11] (which is equivalent to use the [RR.sub.T] Nyquist traces to analyze the circuit) allows to get some very useful parameters as gain margin, loaded quality factor ([Q.sub.L]), which in fact is directly related to phase noise, and the possibility to assure the necessary and sufficient condition for a proper start-up of the oscillator.
Based on this value (Landau et al., 1997), some robustness measures like gain margin, modulus margin can be calculated.
The gain margin and phase margin are 6.64 and 63.92o, respectively.
At the same time, rising production and transportation costs are forcing some national brand manufacturers to downsize their products, in an attempt to gain margin. As a result private labels sometimes offer much better quality, he notes.
Once the linear oscillation criteria are established for the open-loop cascade, the loop is closed, and the oscillation level builds until the device nonlinearity absorbs the excess gain margin at the phase-zero crossing frequency.
Most mass merchants commonly use big-title new releases as loss leaders, so they must rely on other titles--like direct-to-video--to gain margin.
The Bode phase diagram is superimposed on the magnitude plot for easy calculation of phase margin or gain margin. Printer support of the graphics display is provided for Epson nine-pin, dot-matrix printers.
On the other hand, the linear simulation can only estimate the oscillation frequency, gain margin and oscillator [Q.sub.L] (loaded quality factor), but neither the output power nor phase noise or harmonic levels can be estimated.