PURPOSE: To reduce the variance of the oscillation frequency due to temperature change by inverting and amplifying a voltage corresponding to the current flowing to the resistance connected to a MOSFET and adding the output to a prescribed control signal and applying the result to a voltage controlled oscillating circuit.

CONSTITUTION: A voltage VO is generated at a contact 9 in accordance with a drain current ID flowing to a resistance 8 through a P-channel MOSFET 7. This voltage VO is inverted and amplified by an amplifying circuit 16 consisting of an operational amplifier 5 and resistances 3 and 4 and is inputted to a terminal 11 and is superposed on a control voltage. When the temperature rises, the oscillation frequency of a ring oscillator type voltage controlled oscillating circuit 12 is reduced, and the drain current ID of the FET 7, namely, the voltage VO is reduced. When the voltage VD is reduced, the output voltage of the circuit 16 rises because the voltage VO is inverted and amplified. Thus, the voltage applied to the terminal 11 rises and the oscillation frequency of the circuit 12 rises according as the temperature rises. As the result, the oscillation frequency of the circuit 12 is fixed independently of the temperature rise.