Abstract: A third overtone crystal oscillator has an oscillator IC and a crystal element accommodated in a container. The IC includes transistor grounded at its emitter, a first capacitor connected to the base of the transistor via a DC blocking capacitor and to the ground potential, and a second capacitor connected between the collector of the transistor and the ground potential. Both ends of the crystal element are connected to non-grounded ends of the first and second capacitors, respectively. A spiral inductor forming a parallel resonant circuit together with the first capacitor, is provided at the container, using a printing process, for example, being independent of the IC. The parallel resonant frequency of the parallel resonant circuit is set higher than the oscillation frequency at the fundamental wave of the crystal element, and lower than the oscillation frequency at the third overtone of the crystal element.

Abstract: A third overtone crystal oscillator has an oscillator IC and a crystal element accommodated in a container. The IC includes transistor grounded at its emitter, a first capacitor connected to the base of the transistor via a DC blocking capacitor and to the ground potential, and a second capacitor connected between the collector of the transistor and the ground potential. Both ends of the crystal element are connected to non-grounded ends of the first and second capacitors, respectively. A spiral inductor forming a parallel resonant circuit together with the first capacitor, is provided at the container, using a printing process, for example, being independent of the IC. The parallel resonant frequency of the parallel resonant circuit is set higher than the oscillation frequency at the fundamental wave of the crystal element, and lower than the oscillation frequency at the third overtone of the crystal element.

Abstract: A third overtone crystal oscillator includes an oscillator IC and a crystal element. The oscillator IC has an emitter-grounded transistor for oscillation, a first capacitor connected to the base of the transistor via a dc blocking capacitor and to the ground potential; and a second capacitor connected between the collector of the transistor and the ground potential. Both ends of crystal element are connected to the non-grounded ends of the first and second capacitors, respectively. An inductor, which forms a parallel resonant circuit with the first capacitor, is provided as a discrete element separated from the oscillator IC, and the parallel resonance frequency of the parallel resonant circuit formed by the first capacitor and the inductor is set higher than an oscillation frequency of a fundamental wave of the crystal element and lower than an oscillation frequency of a third overtone of the crystal element.