Phase-locked loop. A closed-loop control system that generates an output signal whose phase is related to the phase of an input reference signal. It typically consists of a phase detector, a low-pass filter, and a voltage-controlled oscillator. Engineers use them heavily for clock generation, frequency synthesis, and signal demodulation.
The PLL isn't locking onto the 10 megahertz reference, so the entire clock tree is drifting.
Also heard as
- phase-locked loop
Related terms
VCO
A voltage-controlled oscillator is a circuit that changes its output frequency based on a DC input voltage.
Clock generator
A circuit or chip that produces the primary timing signals for a digital system.
DPLL
A digital phase-locked loop is an electronic circuit that synchronizes a digital output signal with a reference input.
ADPLL
An all-digital phase-locked loop uses purely digital logic to synchronize clock signals.