PLL device with leakage current compensation unit

A current compensation method for a PLL device, comprising:

• providing the PLL device having a reference clock signal and a feedback clock signal;
• providing a current compensation unit;
• when the current compensation unit receiving a phase lock signal from the PLL device, the current compensation unit determines if the reference clock signal leads to the feedback clock signal;
• when the reference clock signal leads to the feedback clock signal, the current compensation unit outputs a compensation current to the PLL device;
• and
• when the reference clock signal synchronizes with the feedback clock signal, the current compensation unit fixes the compensation current at a constant level.

A PLL device with leakage current compensation unit, comprising:

• a PFD unit measuring a phase 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 signal according to the parameter N, wherein a frequency of the feedback signal is N times a frequency of the output signal;
• a phase monitor outputting a phase lead signal or a phase lag signal;
• and
• a current generator coupled to the phase monitor, having a parameter of a settling time, wherein the current generator detects the phase lead signal every the settling time, and when the current generator receives the phase lead signal, the current generator determines and outputs the compensation current, and when the current generator does not receive the phase lead signal, the current generator fixes the compensation current at a constant level.