PURPOSE: To improve the temperature resolution and to reduce the power consumption by measuring an increment of a periodic time of a gate signal at each temperature by means of a measuring pulse with/without frequency division of a reference pulse.

CONSTITUTION: An output of a voltage controlled oscillator(VCO)6 is supplied to a frequency divider 7 and the output of the frequency divider 7 is fed to a multiplexer(Mp)8. The Mp8 is switched by using signals A, B of a counter controller (Cc)9 and the output of the Mp8 is supplied to one input terminal of the OR 2. An output from a temperature sensor 1 is fed to the other input of the OR 2. The output of the OR 2 is supplied to a binary counter (Ct)3 and the output of the Ct3 is fed to a digital control circuit 4 and the Cc9. The Cc9 monitors the output of the Ct3 and outputs a signal switching input terminals D0∼D3 and a signal clearing the Ct3. Moreover, the Cc9 outputs a control signal C to allow the circuit 4 to output a signal only including temperature information only to the VCO 6 via a D/A converter 5 to apply temperature compensation of the output of the VCO 6.