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 crystal oscillator includes an oscillator circuit, a main body, a first switching circuit, a second switching circuit, and a voltage detecting circuit. The oscillator circuit includes an IC chip including an output circuit and a function circuit. The crystal element includes a first excitation electrode and a second excitation electrode. The main body houses the oscillator circuit and the crystal element and includes a power supply terminal, a ground terminal, an output terminal, and a function terminal. The output terminal is electrically connected to the output circuit and the first excitation electrode via the first switching circuit. The function terminal is electrically connected to the function circuit and the second excitation electrode via the second switching circuit. The first switching circuit and the second switching circuit are operated on the basis of a switching signal from the voltage detecting circuit connected to the power supply terminal.

Abstract: A crystal oscillator includes an oscillator circuit, a main body, a first switching circuit, a second switching circuit, and a voltage detecting circuit. The oscillator circuit includes an IC chip including an output circuit and a function circuit. The crystal element includes a first excitation electrode and a second excitation electrode. The main body houses the oscillator circuit and the crystal element and includes a power supply terminal, a ground terminal, an output terminal, and a function terminal. The output terminal is electrically connected to the output circuit and the first excitation electrode via the first switching circuit. The function terminal is electrically connected to the function circuit and the second excitation electrode via the second switching circuit. The first switching circuit and the second switching circuit are operated on the basis of a switching signal from the voltage detecting circuit connected to the power supply terminal.

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.

Abstract: A surface-mount quartz crystal oscillator has a casing substantially in the shape of a substantially rectangular parallelepiped, the casing having a recess defined therein, a pair of upper steps disposed in the recess, a lower step disposed in the recess and having electrically conductive pads thereon, a crystal blank having an end secured to one of the upper steps and an opposite end placed on the other of the upper steps, and an IC chip disposed on the bottom of the recess and electrically connected to the electrically conductive pads by wires according to wire bonding, the IC chip including a circuit, the circuit and the crystal blank jointly making up an oscillating circuit. The wires extend in a direction substantially perpendicular to a longitudinal direction of the casing.

Abstract: A surface-mount quartz crystal oscillator has a casing substantially in the shape of a substantially rectangular parallelepiped, the casing having a recess defined therein, a pair of upper steps disposed in the recess, a lower step disposed in the recess and having electrically conductive pads thereon, a crystal blank having an end secured to one of the upper steps and an opposite end placed on the other of the upper steps, and an IC chip disposed on the bottom of the recess and electrically connected to the electrically conductive pads by wires according to wire bonding, the IC chip including a circuit, the circuit and the crystal blank jointly making up an oscillating circuit. The wires extend in a direction substantially perpendicular to a longitudinal direction of the casing.

Abstract: There is provided a crystal oscillator including a vessel main body having a concave portion, a cover bonded to the vessel main body so as to form an encapsulated vessel together with the vessel main body, a crystal blank held within the vessel, an IC (integrated circuit) chip containing an oscillating circuit utilizing the crystal blank and having a plurality of IC terminals on a major surface thereof, a plurality of circuit terminals formed on a bottom surface of the concave portion of the vessel main body at positions corresponding to the positions of the IC terminals, respectively. The IC chip is fixed to the bottom surface of the concave portion of the vessel main body by effecting face down bonding so that the IC terminals are bonded to the circuit terminals through bumps.