phase-locked loop



  • A circuit which serves to make the phase of an oscillator signal follow the phase of a reference signal. The usual case is that of a local oscillator being locked in phase with an input signal. The phase angles of the two signals are compared utilizing a phase detector, and the appropriate corrective adjustments are made. In this manner, the input signal frequency can be regenerated without any jitter that may have been present. Widely used in frequency control systems, as frequency synthesizers, as demodulators for FM signals, for the synchronization of TV scanning signals, in microwave communications, and so on. Its abbreviation is PLL. Also called phase-lock loop.
  • synonymphase-lock loop