PURPOSE: To attain the temperature compensation of an oscillated frequency by providing an electromagnetic converter controlling a digital code outputted from an A/D converter, an input digital code to a D/A converter and an input digital code to a memory circuit.

CONSTITUTION: A temperature detector 1 detects an ambient temperature and the analog output of the temperature detector 1 is converted into a digital code by an A/D converter 2 and the code is given the a memory circuit 3 as an address signal. When the ambient temperature is changed, the address signal fed to the memory circuit 3 is also changed and a temperature compensation digital code is read from the memory circuit 3. The readout temperature compensation digital code is converted into an analog signal by a D/A converter 4 and fed to a voltage controlled oscillator 5. Then the oscillated frequency of the voltage controlled oscillator 5 is controlled in response to the analog signal voltage.