Patent ID: 7639087

Claim:
A phase-locked loop, comprising: a phase comparator, for receiving an input signal and a feedback signal to compare phases of the input signal and the feedback signal; a charging/discharging unit, connected to the phase comparator, for outputting a control signal according to a comparison result of the phase comparator, wherein the charging/discharging unit comprises a compensation unit for compensating the control signal according to a first compensation value; a low pass filter, connected to the charging/discharging unit, for filtering the control signal output from the charging/discharging unit; a controlled oscillator, connected to the low pass filter, for converting the control signal filtered by the low pass filter to a control current and determining a frequency of an output signal according to the control current, wherein the controlled oscillator comprises a copy unit, connected to the compensation unit, for generating a plurality of candidate currents by copying the control current so as to determine the first compensation value by switching the candidate currents; and a feedback unit, connected to the controlled oscillator, for providing the feedback signal to the phase comparator according to the output signal.