Contents
Where does the phase margin come from in Excel?
While phase margin comes from the phase where the loop gain equals one, the gain margin is based upon the gain where the phase equals -180 degrees.
Why is a 60 degree phase margin important?
A phase margin of 60 degrees is also a magic number because it allows for the fastest settling time when attempting to follow a voltage step input (a Butterworth design). An amplifier with lower phase margin will ring for longer and an amplifier with more phase margin will take a longer time to rise to the voltage step’s final level.
What is the phase margin of an open loop amplifier?
For example, if the amplifier’s open-loop gain crosses 0 dB at a frequency where the phase lag is -135°, then the phase margin of this feedback system is -135° – (-180°) = 45°. See Bode plot#Gain margin and phase margin for more details.
Where is the phase margin in negative feedback?
In its simplest form, involving ideal negative feedback voltage amplifiers with non- reactive feedback, the phase margin is measured at the frequency where the open-loop voltage gain of the amplifier equals the desired closed-loop DC voltage gain.
What is the phase margin of a closed loop system?
Phase margin is defined as the amount of change in open-loop phase needed to make a closed-loop system unstable. The phase margin is the difference in phase between −180° and the phase at the gain cross-over frequency that gives a gain of 0 dB.
What is the gain margin during a phase shift?
Gain margin is defined as the difference between unity and the actual closed-loop voltage gain at the point where a −180° phase shift occurs. To insure stable operation and to allow for variances in component values, the loop gain should fall to about one-third or −10 dB by the time the phase shift has reached −180°.
Is there a way to compensate for phase error?
This paper describes a novel phase error compensation method for reducing the measurement error caused by nonsinusoidal waveforms in phase-shifting methods.