PURPOSE: To easily improve the accuracy of this digital temperature compensated oscillator with simple constitution as necessary by generating a temperature compensating code in each temperature from a memory, D/A converting the code and converting the D/A converted code into DC voltage to control a voltage controlled oscillator 8.

CONSTITUTION: A temperature compensating code read out from a ROM 4 is inputted to an LPF 7 as an 8-bit serial pulse string, e.g. The input is converted into DC voltage matching the high-low rate of the pulse string and the input voltage of the voltage controlled oscillator is controlled by the DC voltage. When the 8-bit pulse string outputs '11101010', the pulse shape becomes a shown graphic (b) and the pulse string is inputted to an LPT to rectify it into DC, so that the oscillator 8 can be controlled. When the number of pulses is increased, voltage to be impressed to the oscillator 8 is increased and vice versa.