Patent ID: 8040197

Claim:
A crystal oscillator comprising: a crystal unit; and a voltage-variable capacitive element that is connected to the crystal unit in series, wherein the crystal oscillator varies an oscillation frequency by applying a control voltage between terminals of the voltage-variable capacitive element and by varying a series equivalence capacitance at a side of an oscillator circuit which is observed between terminals of the crystal unit, wherein the crystal oscillator further comprises a first resistor and a second resistor for dividing the control voltage, wherein at least one of the first resistor and the second resistor is a temperature sensing resistor, the resistance of which changes depending on a temperature, so as to correct frequency temperature characteristics of the oscillation frequency, and wherein the control voltage is set so as to counterbalance the series equivalence capacitance in compliance with frequency temperature characteristics such that the frequency temperature characteristics are corrected within a predetermined standard.