Temperature-compensated piezoelectric oscillator

A temperature-compensated piezoelectric oscillator, comprising:

• a piezoelectric oscillator element;
• an oscillator circuit coupled to the piezoelectric oscillator element, the oscillator circuit oscillating at an oscillation frequency;
• a temperature sensor circuit sensing a temperature of the piezoelectric oscillator element;
• and
• a variable power supply circuit coupled to the temperature sensor circuit and the oscillator circuit, the variable power supply circuit supplying a power supply voltage applied to the oscillator circuit based on an output of the temperature sensor circuit, wherein temperature dependent changes in the oscillation frequency of the oscillator circuit are compensated for by changing the power supply voltage, a frequency-temperature characteristic of the piezoelectric oscillator element being approximated by a function
• f(T)=A(T-25)+B(T-25).sup.2 +C(T-25).sup.3,
• where T is the temperature of the piezoelectric oscillator element, A is a linear coefficient, B is a quadratic coefficient and C is a cubic coefficient, and changes in the oscillation frequency of the oscillator circuit being compensated by temperature characteristic compensating data, the changes in the oscillation frequency corresponding to at least one of the linear coefficient A, the quadratic coefficient B and the cubic coefficient C.