Patent ID: 8610513

Claim:
A crystal oscillator, including a crystal oscillating unit, an amplifier connected in parallel to the crystal oscillating unit, a voltage-variable capacitor element connected to the amplifier, comprising: a temperature compensation circuit, outputting a temperature control voltage to perform a temperature compensation; a frequency control circuit, controlling a frequency according to an input signal; a frequency drift compensation circuit, outputting a frequency drift compensation control voltage that compensates a frequency drift characteristic according to a power consumption; and a constant voltage circuit, approximately maintaining a current consumption of the crystal oscillator constant relative to a variation of a power source voltage of the crystal oscillator, wherein an output from the temperature compensation circuit, an output from the frequency control circuit, and an output from the frequency drift compensation circuit are added and outputted to the voltage-variable capacitor element, wherein the frequency drift compensation circuit outputs the frequency drift compensation control voltage for compensating the frequency drift characteristic according to the power source voltage of the crystal oscillator.