| 摘要 |
PURPOSE:To follow up the wide frequency change of an input signal and to realize the utilization of the satisfactory characteristic with a simple constitution by setting the frequency-dividing ratio corresponding to the frequency component of the input signal after the frequency-dividing ratio corresponding to the phase difference between the input signal and a phase locked loop clock signal is set. CONSTITUTION:A frequency-dividing ratio setting means sets the frequency- dividing ratio corresponding to the phase difference between an input signal and a phase locked loop clock signal and a frequency-dividing ratio adjusting means determines the frequency-dividing ratio based on the frequency component of the input signal. When a phase difference is detected by a frequency-dividing ratio switching means, first, the frequency-divider is operated based on the frequency-dividing ratio set by a frequency-dividing ratio adjusting circuit, and thereafter, the frequency-divider is operated by the frequency dividing ratio set by the frequency-dividing ratio adjusting means. Thus, with a simple constitution, the device can follow up the wide frequency change of the input signal, can correspond with a satisfactory characteristic and the clock deviation phenomenon can be prevented. |
