PURPOSE: To oscillate two different frequencies in one oscillating circuit by switching, by varying charging and discharging currents of the oscillating circuit to binary in accordance with an input control pulse.

CONSTITUTION: A current source 1 for charging is connected to a constant current source 6 in current mirror. The current of the current source 1 for charging is controlled by the constant current source 6, and the current of the sum of currents of a constant current source 7 and a constant current source 8 is flowed to the constant current source 6. Consequently, the constant current source 8 is turned on or off by an input pulse IN to vary the current flowed to the constant current source 6 to binary. Thus, the current charged to a capacitor 5 from the current source 1 for charging is varied to binary. The discharging current of a current source 2 for discharing is varied to binary similarly while interlocking with the current source 1 for charging. Consequently, the oscillated frequency is varied to binary.