Auto-gain controlled digital phase-locked loop and method thereof

摘要

A digital PLL system includes a first multiplier coupled to a phase difference signal for multiplying the phase difference signal by a first gain factor; a second multiplier coupled to the phase difference signal for multiplying the phase difference signal by a second gain factor; a digital loop filter coupled to the first multiplier and the second multiplier for providing an integral signal and a proportional signal and for generating a control signal according to the integral signal and the proportional signal; and an auto-gain control (AGC) unit coupled to the first multiplier, the second multiplier, and the digital loop filter. The AGC unit further comprises a first control unit for updating the first gain factor according to the integral signal; and a second control unit for updating the second gain factor according to the proportional signal.