PURPOSE: To use a prescaler operated in a certain frequency range at a higher or a lower frequency by providing a frequency-voltage conversion circuit on a device and change the current of the frequency divider circuit in response to the input frequency of the frequency divider circuit.

CONSTITUTION: Since the operating frequency range of a prescaler 1 almost depends on the self-running oscillating frequency, the self-running oscillating frequency is made variable in order to vary the operating frequency range of the prescaler 1. By utilizing this characteristic, a frequency-voltage conversion circuit 2 outputting a higher voltage as the frequency is high is added to the prescaler 1 as a control circuit and an input signal to the prescaler 1 is added also to the frequency-voltage conversion circuit 2 and its output is applied to a current control terminal VCS of the prescaler 1. Thus, the current of the prescaler 1 is changed in response to the input signal frequency is changed to make the input sensitivity characteristic of the prescaler 1 wide apparently.