Nihon Dempa Kogyo Co., Ltd.

Tatsunori Onzuka

Toshimasa Tsuda

Yasushi Yamamoto

Junichiro Yamakawa

Kenji Kawahata

Hiroshi Hoshigami

Kazuo Akaike

Susumu Yoshimoto

Mikio Takano

Kietsu Saito

Ryouichi Fujiyama

An object is to obtain a steep and large attenuation amount in attenuation bands close to each other out of a band of a TV wave and to provide a filter in which the use number of inductors is reduced thereby to be able to contribute to downsizing of a device. Elastic wave resonators of a plurality of parallel arms for each forming plurality of attenuation band are connected to the same electric potential point in a signal path without aid of an inductor. Otherwise, a series circuit of a plurality of element parts generating series resonance is connected in a signal path as a parallel arm. Therefore, a large attenuation amount can be obtained in each of the plural attenuation bands, but a region equivalent to what is called a zero point exists between adjacent poles. However, there can be obtained a characteristic in which steep attenuations occur in both sides of the zero point even if the zero point exists. Sets of elastic wave resonators (sets of resonators) connected to the same potential points or parallel arms constituted by the series circuits are connected in a signal path in a plurality of stages, and an inductor for inverting a phase intervenes between the stages.

Filter, portable terminal and electronic component

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

To provide a voltage controlled oscillator having small size and capable of obtaining a low phase noise characteristic over a large span of adjustable range of frequency. A quartz crystal having a characteristic (dielectric loss tangent: tan &#x3b4;) better than that of fluorocarbon resin, LTCC or the like conventionally used as a substrate of a resonance part, and on which a fine pattern of metal film can be formed through a photolithography method, is used as a quartz-crystal substrate, and a conductive line is formed on the quartz-crystal substrate to form an inductance element in the resonance part. Accordingly, since the resonance part having a high Q value can be formed, it is possible to obtain a voltage controlled oscillator having small size and low loss over a wide frequency range.

Voltage controlled oscillator and electronic component

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).

A ladder SAW (surface acoustic wave) filter which includes a first SAW resonator disposed in a parallel arm and a second SAW resonator disposed in a series arm, has an inductor connected parallel to at least one of the first SAW resonator and the second SAW resonator. The frequency of a resonance point or an anti-resonance point of the at least one of the first SAW resonator and the second SAW resonator is adjusted by changing the inductance value of the inductor.

Growing community of inventors

Sayama, Japan

Tatsunori Onzuka