Nihon Dempa Kogyo Co., Ltd.

Hiroshi Hoshigami

Kazuo Akaike

Toshimasa Tsuda

Kenji Kawahata

Tatsunori Onzuka

Junichiro Yamakawa

Takashi Nakaoka

Yasushi Yamamoto

Kaoru Kobayashi

Susumu Yoshimoto

Kietsu Saito

Mikio Takano

Mohd Hafidz Bin Ahmad Adlan

Ryouichi Fujiyama

An crystal resonator includes a first oscillating circuit that oscillates a crystal resonator at a first frequency, a first impedance adjusting circuit that adjusts an impedance of a first oscillating system including the crystal resonator and the first oscillating circuit, a second oscillating circuit that oscillates the crystal resonator at a second frequency that is different from the first frequency, a second impedance adjusting circuit that adjusts an impedance of a second oscillating system including the crystal resonator and the second oscillating circuit, and a controlling circuit that controls the first impedance adjusting circuit and the second impedance adjusting circuit.

Crystal oscillator and method of manufacturing crystal oscillators

A differential oscillator includes a resonator, a differential amplifier circuit, and a filter. The filter is disposed in parallel to the resonator and the differential amplifier circuit. The filter has a first resonance frequency in the first resonance mode and a second resonance frequency in the second resonance mode. The filter has a lower impedance at one frequency in one of the first resonance frequency and the second resonance frequency than an impedance at one frequency at another in the first resonance frequency and the second resonance frequency. The differential oscillator has a negative resistance at a frequency at which the impedance of the filter is higher while the differential oscillator does not have a negative resistance at a frequency at which the impedance of the filter is lower among the first resonance frequency and the second resonance frequency.

Differential oscillator

There is provided a voltage controlled oscillator that is compact and can be manufactured at low cost. The voltage controlled oscillator is structured to include: a resonance part including a variable capacitance element and an inductance element, the variable capacitance element having a capacitance that varies according to a control voltage for frequency control input from an external part, and a series resonant frequency of the resonance part being adjusted according to the capacitance; an amplifying part amplifying a frequency signal from the resonance part; and a feedback part including a capacitance element for feedback and feeding the frequency signal amplified by the amplifying part back to the resonance part to form an oscillation loop together with the amplifying part and the resonance part, wherein the amplifying part is provided in an integrated circuit chip, and the resonance part and the capacitance element for feedback are formed as circuit components separate from the integrated circuit chip. The circuit components are selected according to an oscillation frequency.

Voltage controlled oscillator

Provided is a fundamental wave/overtone crystal oscillator to obtain fundamental wave oscillation and overtone oscillation with one crystal unit and to optimize the excitation current depending on the fundamental wave oscillation and the overtone oscillation. The fundamental wave/overtone crystal oscillator includes a crystal unit that oscillates with fundamental waves or with overtones, and an oscillator circuit that amplifies an excitation current from the crystal unit and outputs an oscillatory frequency. A capacitor Cf and a capacitor Co are connected in parallel with the base of a transistor in the oscillator circuit as well as the emitter. A switch is provided so as to connect or disconnect the capacitor Cf with respect to the circuit in response to a switching signal. The switch turns ON when the crystal oscillator oscillates with fundamental waves, and turns OFF when the crystal oscillator oscillates with overtones.

Fundamental wave/overtone crystal oscillator

To provide a voltage controlled oscillator capable of being treated as a lumped constant circuit, having small size and capable of obtaining an oscillation frequency in a high frequency band. A resonance part in a voltage controlled oscillator has variable capacitance elements whose electrostatic capacitance varies in accordance with a control voltage for frequency control input from the outside and an inductance element, an amplifying part amplifies a frequency signal from the resonance part, and a feedback part, having feedback capacitance elements, forms an oscillation loop together with the amplifying part and the resonance part by making the frequency signal amplified in the amplifying part to be fed back to the resonance part. Further, the resonance part and the feedback part are provided on a quartz-crystal substrate.

There is provided a voltage controlled oscillator using a Colpitts circuit capable of suppressing deterioration (decrease) in variable range (adjustable range) of an output frequency due to the influence of an inductance component on a conductive line, which connects a connection point between two capacitors of a feedback part and an emitter of a transistor. In a VCO using a Colpitts circuit, with respect to capacitorsof a feedback part, a first feedback capacitance element (capacitor)is disposed so as to directly couple a terminal for base (connection part) and a terminal for emitter on a base substrate, to which a terminal part(T) extending from a base of a transistorand a terminal part(T) extending from an emitter of the transistorare fitted, respectively, and a second feedback capacitance element (capacitor)is disposed so as to directly couple the terminal for emitter and the terminal for grounding (ground electrode).

Growing community of inventors

Sayama, Japan

Hiroshi Hoshigami