PURPOSE: To fix a voltage against the variance of temperature or the like by flowing the voltage, which determines the oscillation frequency and the conversion gain of a voltage controlled oscillating circuit, to a resistance to fix the voltage generated in the resistance.

CONSTITUTION: When the voltage of an input terminal 31 is changed, currents of transistors TRs 12 and 13 are changed, and the collector current of a TR 8 on the turning-on side of a TR 9 is changed, and as the result, the voltage generated in a resistor 24 or 25 is changed. For the purpose of preventing this change, namely, generating a certain voltage in resistors 24 and 25, the current is pulled from an auxiliary current source circuit 2. That is, a TR 15 is turned on to pull the current from the circuit 2 so that the voltage generated in the resistor 24 is fixed when the TR 8 is turned on to pull the current from the resistor 24. When the TR 9 is turned on to pull the current from the resistor 25, a TR 14 is turned on to pull the current from the circuit 2 so that the voltage generated in the resistor 25 is fixed. Thus, the voltage generated in resistors 24 and 25 is not varied.