Murata Manufacturing Co., Ltd.

Haruo Morii

Michio Kadota

Kazuhiko Morozumi

Hideya Horiuchi

Junya Ago

Seigo Hayashi

Kimio Masaie

Chikashi Kondo

A surface acoustic wave filter includes a glass substrate, an interdigital transducer provided on the glass substrate, a piezoelectric film arranged on the glass substrate so as to cover the interdigital transducer; a terminal electrode provided on the glass substrate and electrically connected to the interdigital transducer; and a coating film having an area smaller than that of the terminal electrode. The coating film is arranged on the terminal electrode such that a portion of a top surface of the terminal electrode is exposed throughout the periphery thereof.

Surface acoustic wave filter with terminal electrode coating film

A surface acoustic wave filter apparatus includes a plurality of stages of multi-mode filters defined by edge-reflection type surface acoustic wave devices and electrically connected in series with each other. The plurality of stages of multi-mode filters are provided on a common piezoelectric substrate and arranged in a direction which is substantially perpendicular to the propagation direction of surface acoustic waves. Ground electrodes are located between the stages of the plurality of stages of multi-mode filters.

Multi-mode edge reflection saw filter device with ground electrodes between stages, duplexer, and communication device

An edge reflection longitudinally coupled surface acoustic wave filter utilizing an SH-type surface wave includes a piezoelectric substrate having two opposing edge surfaces, and first and second interdigital transducers each having a plurality of electrode fingers and being arranged on the piezoelectric substrate such that a shear horizontal surface wave excited by one of the first and second interdigital transducers is reflected between the two opposing edge surfaces to form a standing wave. Attenuation poles of frequency characteristics of the first and second interdigital transducers are adjacent to the frequency position of spurious responses determined by the distance between the two opposing edge surfaces.

Edge reflection type longitudinally coupled surface acoustic wave filter

A transversal-coupled resonator type surface acoustic wave filter includes a piezoelectric substrate and first and second interdigital transducers. The piezoelectric substrate has a pair of substrate edges which are substantially parallel to each other and reflect a shear horizontal type surface wave excited and propagated on a surface of the piezoelectric substrate in a direction perpendicular to the substrate edges. The first and second interdigital transducers have the same resonance characteristics and are provided on the piezoelectric substrate. Each of the first and second interdigital transducers includes a pair of outermost electrode fingers which are arranged to be flush with the substrate edges of the piezoelectric substrate, respectively and a pair of adjacent electrode fingers which are adjacent to the pair of the outermost electrode fingers, respectively. A distance D' from one of the substrate edges of the piezoelectric substrate to a center of the corresponding adjacent electrode fingers satisfies the following inequalities:

Surface acoustic wave filter

Two surface acoustic wave resonators are transversely formed with a minute spacing between them on a piezoelectric substrate. Said two surface acoustic wave resonators are oppositely formed to each other to become line-symmetry. Each of the surface acoustic wave resonator comprises an interdigital transducer and reflectors formed on its both sides. An input terminal and an output terminal are lead from the corresponding interdigital transducer. Between the input and the output terminals, an electrostatic capacity is bridged. The electrostatic capacity is formed on, for example, a piezoelectric substrate. In this case, the electrostatic capacity may be formed by alternately interdigitating each part of comb-like electrodes of the two interdigital transducers. Furthermore, the electrostatic capacity may be formed by alternately interdigitating both parts of the two reflector electrodes.

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Kanazawa, Japan

Haruo Morii