DIGITALLY CONTROLLED OSCILLATOR CIRCUIT

PURPOSE:To provide a digitally controlled oscillator circuit for sharing control parts in a portable telephone set and compensating the temperature of a crystal oscillator. CONSTITUTION:In this digitally controlled oscillator circuit 22 of a portable telephone set for switch a CPU 1, a memory 20, a temperature sensor 23, a D/A converter 21 and an A/D converter 24 are used as the control parts, control information for correcting the deviation of the temperature and the output frequency of the portable telephone set is stored in the memory 20 beforehand, the temperature of the oscillator circuit 22 is detected by the temperature sensor 23 and a signal converted in the A/D converter 24 is inputted to the CPU 1. The CPU 1 outputs a correction signal corresponding to the control information. stored in the memory 20, the correction signal is converted into an analog value in the D/A converter 21 and inputted to the oscillator circuit 22 as a control voltage and the output frequency of the portable telephone set is constantly controlled to a prescribed frequency.