Patent ID: 7005934

Claim:
A temperature compensated crystal oscillator comprising: a oscillation circuit that has a piezoelectric vibrator having a piezoelectric element which is excited in a predetermined frequency, and an oscillation amplifier that excites the piezoelectric element by flowing a current to the piezoelectric element; a vibrator current controller that controls a current of the piezoelectric vibrator; a temperature compensation circuit that compensates for temperature characteristics of the piezoelectric vibrator; and a variable capacitance diode that changes the oscillation frequency by changing the load capacitance of the oscillation circuit using an external voltage, wherein the temperature compensation circuit generates a functional voltage that compensates for the temperature characteristics of the piezoelectric vibrator, and inputs the functional voltage to the vibrator current controller, thereby to control the vibrator current to change the oscillation frequency of the oscillation circuit so as to compensate for the temperature characteristics of the piezoelectric vibrator, and the temperature compensation circuit changes an application voltage of the variable capacitance diode using the external voltage, thereby to change the oscillation frequency of the oscillation circuit.