Patent ID: 7741924

Claim:
A temperature-compensated crystal oscillator comprising: an oscillation circuit including an oscillator; a temperature detector; a voltage variable capacitance element coupled to an oscillation loop of the oscillation circuit; and a temperature compensation circuit configured to apply a compensation voltage to the voltage variable capacitance element to compensate a temperature change in response to temperature data detected by the temperature detector, wherein the temperature compensation circuit has a plurality of correction point data, the respective correction point data being set in advance for each divided temperature zone, and wherein the temperature compensation circuit obtains: a first-order coefficient of a first correction point data in a lower temperature zone by performing a subtraction between a second correction point data in a higher temperature zone and a third correction point data in a further lower temperature zone than the first correction point data in the lower temperature zone, and a first-order coefficient of the second correction point data in the higher temperature zone by performing a subtraction between the first correction point data in the lower temperature zone and a fourth correction point data in a further higher temperature zone than the second correction point data in the higher temperature zone; selects a first correction point data in a lower temperature zone and a second correction point data in a higher temperature zone, as compared with the detected temperature data, performs an interpolation between the first and second correction point data by a weighted averaged first-order interpolation, and generates the compensation voltage.