Temperature-compensated crystal oscillator

A temperature-compensated crystal oscillator comprising:

• a crystal resonator;
• and
• an oscillator circuit for performing temperature compensation,
• the oscillator circuit having
• a temperature sensor unit that measures an ambient temperature of the crystal resonator,
• a temperature compensation unit, to which the temperature sensor unit outputs the measured temperature, outputs a first voltage for temperature compensation based on the measured temperature,
• a high-temperature temperature sensor unit that measures an ambient temperature of the crystal resonator in a high temperature area exceeding a particular temperature range,
• a high-temperature load capacitance adjustment unit, to which the high-temperature temperature sensor unit outputs the temperature measured in the high temperature area exceeding the particular temperature range, outputs a second voltage for temperature compensation based on the temperature measured in the high temperature area exceeding the particular temperature range,
• an oscillator unit having first and second variable capacitance elements used for temperature compensation within the particular temperature range, and third and fourth variable capacitance elements used for temperature compensation in the high temperature area, wherein the oscillator has only two voltage input terminals including a first input terminal and a second input terminal, so that temperature compensation is performed by inputting the first voltage through the first input terminal, and temperature compensation is also performed by inputting the second voltage in the high temperature area through the second input terminal, an end of the first variable capacitance element and an end of the second variable capacitance element are directly grounded, and an end of the third variable capacitance element and fourth variable capacitance element are directly grounded, and
• a buffer that amplifies the output from the oscillator unit.