Patent ID: 7205847

Claim:
A phase locked loop (PLL) system for generating a reference clock to write recording data on an optical medium, the PLL system comprising: a clock generator generating the reference clock according to a phase difference between the reference signal and a first frequency-divided signal; a phase-shift detector generating a phase adjusting signal; and a phase-controllable frequency divider dividing the frequency of the reference clock to generate the first frequency-divided signal, and receiving the phase adjusting signal to adjust the phase of the first frequency-divided signal; wherein the phase-shift detector comprises: an ADIP sync detector generating an ADIP synchronization signal synchronous to the ADIP units of the optical medium; a frequency divider dividing the reference clock to generate a second frequency-divided signal; and a phase difference detector detecting a phase difference between the second frequency-divided signal and the ADIP synchronization signal to generate the phase adjusting signal.