PURPOSE: To suppress a rapid frequency change in digital temperature compensation by using a peac element, a switch resistor array and a capacitive element for switching noise elimination.

CONSTITUTION: A capacitor 25 added to eliminate a switching noise is provided the oscillator. With switches 16∼19 thrown to decrease a combined resistance RX, of resistors 3∼6 depending on the switches. 19 as the ambient temperature increases, the bias voltage is being decreased. As a result, the total capacitance CP of the peac element is lowered and the oscillated frequency is increased as shown in solid lines f0. When the frequency temperature characteristic of the crystal vibrator is shown in broken lines f0', the frequency of an output signal at an output terminal 11 of the crystal oscillation circuit is shown in broken lines f0", which shows the compensated frequency temperature characteristic.