Hitachi, Ltd.

Tetsuya Hirashima

Jun Yamada

Mitsutaka Hikita

Nobuhiko Shibagaki

Akitsuna Yuhara

Toyoji Tabuchi

Hitoshi Watanabe

Kazuhito Kurosawa

Jun Sasaki

A surface acoustic wave device is disclosed for use in a communication apparatus where the surface acoustic wave device has a multiple of surface acoustic wave elements with different filter characteristics formed on mutually distinct piezoelectric substrates. The different filter characteristics combine to form filters having desired filter characteristics.

Surface acoustic wave filter device formed on a plurality of

At least one electro-acoustic transducer of a first surface acoustic wave device and acousto-electric transducers of a second surface acoustic wave device are arranged symmetrically to the first surface acoustic wave device about a line parallel to a propagating direction of surface acoustic wave and is phase-weighted differently from the remaining transducers having common phase-weighting, to improve an attenuation for stop frequency.

Surface acoustic wave band-pass filter with different phase weighted

When SAW filter is used as a receiving filter of an antenna duplexer filter in a cellular radio equipment, since a transmitting signal of an out-band frequency has a large power for the SAW filter, the large power can leak into the SAW filter to generate inter-modulation disturbances in the SAW filter. Since the inter-modulation disturbances are generated when the transmission power density of the surface acoustic wave is made too large, input converters are divided, and the divided converters are disposed in the direction perpendicular to the propagation direction of the surface acoustic wave to lower the transmission power density. Since the divided converters are connected in series, reduction in the impedence together with increase of the aperture length can be compensated.

Surface acoustic wave filter

In a SAW device comprising a piezoelectric substrate and at least one set of metallic electrodes formed on the piezoelectric substrate, at least one set of the electrodes have a laminated structure comprised of a layer of an aluminum film added with an impurity at a concentration of 6 wt. % or less and another layer of a film of pure aluminum or aluminum added with an impurity at a concentration of 0.4 wt. % or less. The SAW device having the laminated structure of electrodes can handle high frequency electric signals of higher power and/or larger amplitudes.

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Katsuta, Japan

Tetsuya Hirashima