Method and device for protecting a PLL in reading signals on a defect disc

A device for adjusting a phase lock loop (PLL) in reading signals on a defect optical disc, said device comprising:

• a defect detection unit, receiving a plurality of defect detection signals for setting a plurality of defect flag signals, wherein said plurality of defect detection signals comprise at least an envelope of a RF signal and bit modulation signals;
• and
• a logic combination unit, performing an logic operation on said defect flag signals in order to detect a specified defect;
• and
• a PLL in electrical communication with the logic combination unit, wherein said PLL comprises:
• a charge-pump with different charge-pump current sources selectable to provide different bandwidths for avoiding PLL frequency-shift caused by said specified defect while said specified defect is detected;
• and
• a low pass filter for receiving an output of the charge-pump and generating a control voltage output;
• and
• a voltage controlled oscillator (VCO) for receiving the control voltage output from the low pass filter, the VCO configured to provide different resistances which are adjusted to provide different bandwidths for avoiding PLL frequency-shift caused by said specified defect when said specified defect is detected.