Circuit for generating a binary wobble signal, the write clock generating circuit, a method for generating a binarized wobble signal, a write clock generation method and an optical disc apparatus

摘要

PROBLEM TO BE SOLVED: To provide a write clock generation circuit capable of detecting a wobble signal with high accuracy even when the changeover operation is performed from reproduction to recording and also capable of generating proper write clocks having small jitter.;SOLUTION: In this write clock generation circuit, the gain fluctuation of a wobble signal amplitude-constant AGC (automatic gain control) circuit is made smooth by suppressing the change of a wobble signal from just before the start of the recording to just after the start of the recording while generating write clocks from the wobble signal obtained by changing the gain of the VGA (variable gain amplifier) of the post stage of divided light receiving elements by stages with gain control circuits in the fixed period of just after the start of recording due to a changeover from the reproduction to the recording. Thus, write clocks in which the fluctuation in higher frequencies of a wobble frequency is suppressed and have small fitter are generated even when the changeover operation is performed from the reproduction to the recording.;COPYRIGHT: (C)2003,JPO