Patent ID: 8344816
Filing Date: 2013-01-01
Classification: H03B

Abstract:
1. A fundamental wave/overtone crystal oscillator including a crystal unit that can oscillate with fundamental waves or with overtones, and an oscillator circuit that amplifies an excitation current from the crystal unit and outputs an oscillatory frequency, wherein the oscillator circuit comprises a transistor having a base and an emitter, the transistor amplifying the excitation current, a first capacitor and a second capacitor are connected in parallel the first capacitor having one end connected with the base of the transistor to which the excitation current is input and the second capacitor having one end connected with the base, and the other end of the first capacitor and the other end of the second capacitor are connected with the emitter of the transistor, a third capacitor and a first resistor are connected in parallel, the third capacitor having one end connected with the emitter and the first resistor having one end connected with the emitter, and the other end of the third capacitor and the other end of the first resistor are grounded, a first switch is disposed, the first switch turning OFF to disconnect the first capacitor from the oscillator circuit in response to a signal input or turning ON to connect the first capacitor to the oscillator circuit in response to a signal input, the first switch turns ON when the fundamental wave/overtone crystal oscillator oscillates with fundamental waves, and turns OFF when the fundamental wave/overtone crystal oscillator oscillates with overtones, a switch circuit is disposed between the crystal unit and the oscillator circuit, wherein the switch circuit includes a second resistor and a second switch, and when the fundamental wave/overtone crystal oscillator oscillates with fundamental waves, the second switch is switched so that an excitation current input from the crystal unit is output to the oscillator circuit via the second resistor, and when the fundamental wave/overtone crystal oscillator oscillates with overtones, the second switch is switched so that an excitation current input from the crystal unit is output to the oscillator circuit not via the second resistor.