PURPOSE: To reduce the total power consumption by using a witch so as to apply a DC level to an input terminal of a 1st stage frequency divider circuit thereby stopping the frequency division operation when an output signal from an oscillator is selected.

CONSTITUTION: When a multiplexer MUX 20 uses a frequency fosc of an oscillator 10 as an output signal fout, a DC level is fed to an input terminal of a frequency divider 12 by a switch 26 to stop the operation of frequency dividers 12, 14, 16, 18 thereby reducing the power consumption. Furthermore, when any of outputs fosc/2-fosc/16 of specific frequency dividers is used for an output signal fout to select the MUX 20, a 2nd contact of a switch provided to a pre-stage of the specific frequency dividers 12, 14, 16, 18 is connected to a 2nd point, an output signal from the oscillator 10 or a signal frequency-dividing the signal is fed to the frequency divider. Then the 3rd point of the switch just after the selected frequency divider connects to ground and a DC level is applied to the frequency divider just after, then the frequency division of the frequency divider of a post stage is stopped. Thus, the power consumption for the overall operation is reduced.