CIRCUIT FOR COMPENSATING A TEMPERATURE IN A CRYSTAL OSCILLATOR

摘要

PURPOSE: A circuit for compensating a temperature in a crystal oscillator is provided to prevent a frequency hopping by adding a varacter diode to make a capacitance provided be changed continuously. CONSTITUTION: A capacitor circuit is formed by parallel connecting a plurality of serial circuit that is composed of a plurality of switching elements(D0,D1...D7) and a plurality of fixed capacitors(C0,C1...C7) between an input terminal and a ground of a crystal resonator(120). The each fixed capacitor has different multiple capacitance of a unit capacitance. A varacter diode is connected between the input terminal and the ground of the crystal resonator(120). A voltage appling device changes a capacitance of the varacter diode linearly. A signal controller(140) selects one frequency(f0) of a clock signal generates two-frequency divided signal(f0/2). The signal controller provides f0 or f0/2 on the basis of a change of the data.