Patent ID: 7742554

Claim:
A PLL device with a leakage current compensation unit, comprising: a PFD unit measuring a phase difference and a frequency difference between a reference clock signal and a feedback clock signal of the PLL device to output a difference signal UP and a difference signal DN; a charging pump circuit receiving and transferring the difference signals UP and DN into a current; a loop filter receiving and transferring the current into a voltage; a voltage controlled oscillator receiving the voltage and outputting an output signal; a feedback divider having a parameter N, receiving the output signal and generating the feedback clock signal according to the parameter N, wherein a frequency of the feedback clock signal is N times a frequency of the output signal; and the current compensation circuit receiving the reference clock signal and the feedback clock signal, or the difference signals UP and DN, determining and outputting a compensation current to the loop filter responsive to the reference clock signal leading the feedback clock signal or the difference signal UP leading the difference signal DN, and fixing the compensation current at a constant level responsive to the reference clock signal synchronizing with the feedback clock signal or the difference signal UP synchronizing with the difference signal DN.