Search results
Results From The WOW.Com Content Network
Bode plot illustrating phase margin. In electronic amplifiers, the phase margin (PM) is the difference between the phase lag φ (< 0) and -180°, for an amplifier's output signal (relative to its input) at zero dB gain - i.e. unity gain, or that the output signal has the same amplitude as the input.
Figure 9 is the phase plot. Using the value of f 0 dB = 1 kHz found above from the magnitude plot of Figure 8, the open-loop phase at f 0 dB is −135°, which is a phase margin of 45° above −180°. Using Figure 9, for a phase of −180° the value of f 180 = 3.332 kHz (the same result as found earlier, of course [note 3]).
Conversely, a phase reversal or phase inversion implies a 180-degree phase shift. [ 2 ] When the phase difference φ ( t ) {\displaystyle \varphi (t)} is a quarter of turn (a right angle, +90° = π/2 or −90° = 270° = −π/2 = 3π/2 ), sinusoidal signals are sometimes said to be in quadrature , e.g., in-phase and quadrature components of a ...
The phase margin is the departure of the phase at f 0 dB from −180°. Thus, the margin is: = (/) (/). Because f 0 dB / f 1 = βA 0 ≫ 1, the term in f 1 is 90°. That makes the phase margin:
that is, the sum of the angles from the open-loop zeros to the point (measured per zero w.r.t. a horizontal running through that zero) minus the angles from the open-loop poles to the point (measured per pole w.r.t. a horizontal running through that pole) has to be equal to , or 180 degrees.
This formula was first obtained by B.A. Vvedenskij. [3] Note that the power decreases with as the inverse fourth power of the distance in the far field, which is explained by the destructive combination of the direct and reflected paths, which are roughly of the same in magnitude and are 180 degrees different in phase.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
It must have a maximum phase shift of more than 180 degrees at high frequencies so the phase shift at the desired oscillation frequency can be 180 degrees. The most common phase-shift network cascades three identical resistor-capacitor stages that produce a phase shift of zero at low frequencies and 270° at high frequencies. The first ...