| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problems wherein a phase-locked loop circuit which is to extract a signal locked to track the wobble of a recordable optical disk is slow to be locked-in state because an input signal is not locked-in without reaching a reference frequency, and that lock detection cannot be performed if a demodulation signal cannot be read. <P>SOLUTION: A lock-in function is realized by making a counter for performing an up/down count change its counting state when a phase reference signal is continuous or the input signal is continuous. And lock detecting means is realized by changing a count direction from a state of entering a lock area to the other state of entering an unlock area after dividing a phase of phase-locked clock into a plurality of areas. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
