PLL circuit pull-in circuit, PLL circuit pull-in method, and optical disk reproducing apparatus

摘要

A PLL circuit, to which an input signal is inputted, is provided with: a voltage controlled oscillator for outputting an output signal; a control voltage generation circuit for generating a control voltage to lock phases of the input and output signals by a loop, and outputting the generated control voltage to a control input terminal of the voltage controlled oscillator; and a central frequency setting circuit for setting a central frequency, to which a frequency of the output signal is to be pulled-in, to the control voltage generation circuit. A pulling-in circuit for the PLL circuit is provided with: a sweep range setting circuit for setting a sweep range, where the frequency of the output signal is to be pulled-in to the set central frequency, on the basis of the set central frequency; a lock detector for detecting whether or not a pulling-in operation is completed in the PLL circuit, and outputting a lock signal when the pulling-in operation is detected to be completed; and a sweep range control circuit for controlling the control signal generation circuit to generate the control signal to repeatedly sweep the frequency of the output signal through the set sweep range during the pulling-in operation until the lock signal is supplied thereto.