Other

Ngk Insulators, Inc.

Mitsui Minings & Melting Co., Ltd.

Mitsubishi Jukogyo Kabushiki Kaisha

Asahi Kasei Kogyo Kabushiki Kaisha

Asahi Kasei Kabushiki Kaisha

Nihon Dempa Kogyo Co., Ltd.

Acoustic Wave Device Labo., Ltd.

Kazuhiko Yamanouchi

Mitsuhiro Tanaka

Hiroyuki Odagawa

Masao Takeuchi

Naohiro Kuze

Yasuhito Kanno

Yoshihiko Shibata

Yasufumi Horio

Shunji Kato

Junichi Ogata

Kenji Suzuki

Hiroyuki Kato

Masatsugu Oshima

Masahiko Sugiyama

Keiichi Morishita

Hiromu Terada

Wasuke Sato

Hiromasa Goto

Norihito Mihota

An acoustic wave element which can be reduced in size and produced relatively easily, practically used without using harmful substances, and can suppress a surface acoustic wave propagation loss, which has an excellent temperature coefficient of frequency and a velocity dispersion characteristic, and with which an increase in the reflection coefficient of interdigital transducers can be suppressed, and a method for manufacturing the acoustic wave element are provided. The acoustic wave element includes a pair of electrodes provided on both surfaces of a piezoelectric substrate, and a dielectric film provided on a first surface of the piezoelectric substrate so as to cover the electrode. The acoustic wave element alternatively includes interdigital transducers provided on a first surface of the piezoelectric substrate, and a dielectric film provided on the interdigital transducers, a gap between the interdigital transducers, and/or a second surface of the piezoelectric substrate.

Acoustic wave element and method for manufacturing same

A unidirectional surface acoustic wave (SAW) transducer has a substrate which is piezoelectric or electrostrictive, a first IDT (interdigital transducer) electrode disposed on a surface of the substrate and having a plurality of first electrode fingers, and a second IDT electrode disposed on the surface of the substrate and having a plurality of second electrode fingers alternating with the first electrode fingers, and structural elements disposed on the surface of the substrate and arranged periodically in a propagating direction of surface acoustic waves. The structural elements comprise grooves or dielectric films each having a width of &#x3bb;/4 or &#x3bb;/2, for example, where &#x3bb;represents a wavelength corresponding to a fundamental operating frequency of the unidirectional surface acoustic wave transducer.

Surface acoustic wave transducer

In a spread spectrum communication using a long spreading code, a spread spectrum signal processing apparatus is provided, which is suitable for performing communication by using a correlator having a size mountable on a portable equipment. The spread spectrum signal processing apparatus has a correlator for correlating between a spread spectrum signal and a given reference signal, an A/D converter for converting a correlation signal into a digital signal, a memory for storing the digital signal from the AD converter as digital data, a signal processor for summing digital data corresponding to each of divided codes C&#x2013;Cand for outputting a result of summation, and a control unit for controlling to apply each of the divided codes C&#x2013;Cin this order repeatedly as a reference signal to the correlator. The signal processor begins a summing process by making reference to a timing signal from the control unit.

Spread spectrum signal processing apparatus and spread communication system

Disclosed is a surface acoustic wave substrate including: a piezoelectric or electrostrictive substrate having large electromechanical coupling coefficient; and a thin film formed on the substrate and having variation characteristics of frequency of a surface acoustic wave relative temperature variation opposite to that of the substrate. The substrate is a LiNbO substrate having a cut angle of rotated Y plate within a range from &minus;10&deg; to &plus;30&deg; and propagating a piezoelectric leaky surface wave having a propagation velocity higher than that of a Rayleigh type surface acoustic wave along X-axis direction or within a range of &plusmn;5&deg; with respect to X-axis direction. A value of H/&lgr; falls within a range from 0.05 to 0.35, where H is the film thickness of the thin film, and &lgr; is the wavelength of operating center frequency of the piezoelectric leaky surface wave.

Surface acoustic wave substrate and surface acoustic wave functional element

In order to provide a transducer suitable for an anisotropic substrate having the NSPUDT property, on the anisotropic piezoelectric substrate being cut to have the NSPUDT property, there is formed a transducer structure having an exciting electrode structure ( ) and a reflector structure ( ). When &lgr; is a wavelength of a fundamental surface acoustic wave, said exciting electrode structure ( ) includes a positive electrode ( ) having a plurality of electrode fingers arranged at a pitch &lgr; and a negative electrode ( ) having at least one electrode finger interdigitally arranged between said electrode fingers of the positive electrode with a center distance of &lgr;/2. The reflector transducer ( ) includes a plurality of electrode fingers arranged with a center distance of &lgr;/2, and a distance L between said exciting electrode structure ( ) and the reflector structure ( ) is set to L &equals;(2n&plus;1)&lgr;/4 (n being a positive integer).

Surface acoustic wave transducer using NSPUDT property substrate and surface acoustic wave filter using the transducer

A surface acoustic wave functional element is provided that includes a piezoelectric substrate or a multilayer piezoelectric substrate having a large electromechanical coupling coefficient. Semiconductor layers are formed on the piezoelectric substrate. The semiconductor layers include an active layer and a buffer layer. The buffer layer is formed of a structure that has a lattice constant that is the same as or similar to that of the active layer. In addition, input and output electrodes are formed on both sides of the semiconductor layers. The surface acoustic wave functional element attains a large amplification gain at low voltage, and can be used as part of a transmitting/receiving circuit in a high frequency portion of a mobile communication device.

Surface acoustic wave element and electronic circuit using the same

The surface acoustic wave functional element comprises a semiconductor layer provided on a piezoelectric substrate or a piezoelectric film substrate and makes use of interaction between a surface acoustic wave propagating on the substrate and electrons in the substrate layer, but has the semiconductor layer disposed outside above the propagation path for propagating a surface acoustic wave, comprises a plurality of grating electrodes perpendicularly above and to the propagation path and moreover the semiconductor layer comprises an active layer and a buffer layer lattice-matching thereto. By use of this surface acoustic wave functional element, a surface acoustic wave amplifier capable of providing a high amplification gain at a practical low voltage, a surface acoustic wave convolver having a higher efficiency than ever or the like are offered.

Surface acoustic wave functional device

Elastic surface wave functional device and electronic circuit using the

A surface acoustic wave device including a piezoelectric substrate having NSPUDT behavior and a directionality reversed electrode structure including positive electrode, negative electrode and floating electrode. Positive and negative electrode fingers each having a width of .lambda./8 are arranged interdigitally at a pitch of .lambda. and floating electrode fingers having a width of 3 .lambda./8 are arranged between successive positive and negative fingers with an edge distance of .lambda./8. A directivity due to NSPUDT behavior of the substrate can be reversed. Positive and negative electrode fingers are arranged interdigitally at a pitch of .lambda. and between successive positive and negative electrode fingers are arranged floating electrode fingers having a reflecting coefficient different from that of the positive and negative electrodes.

Surface acoustic wave device

A surface acoustic wave device including a substrate made of a lithium tetraborate single crystal (Li.sub.2 B.sub.4 O.sub.7) whose cut and propagating direction are determined such that Euler cut angles (.psi., .theta., .phi.) are .psi.=+5.degree..about.-5.degree., .theta.=9.degree..about.29.degree. and 32.degree..about.86.degree. and .phi.=85.degree..about.95.degree., and an electrode structure formed on a surface of the substrate to realize a natural single-phase unidirectional transducer property together with an anisotropy of said substrate. A lithium tetraborate substrate having cut angles of (0.degree., 51.degree., 90.degree.) shows an ideal NSPUDT and a lithium tetraborate substrate having cut angles of (0.degree., 78.degree., 90.degree.) reveals a zero temperature coefficient of delay. A directionality reversed electrode structure or a directionality corrected electrode structure may be advantageously used.

A surface acoustic wave filter device includes a substrate which includes quartz or the like piezoelectric material having a small temperature coefficient. The substrate has a surface which is formed with interdigital-type unidirectional transducers on input and output sides, each having a positive electrode and a negative electrode. The positive electrodes and the negative electrodes of each of the input side and output side transducers have electrode fingers which are arranged so as to transduce a harmonic wave of a selected order which is higher relative to a fundamental surface acoustic wave.

Surface acoustic wave filter device with symmetrical electrode

In a surface acoustic wave transducer having closely space-apart IDT electrode segments, a metallic oxide is selectively formed only along the marginal edge of each electrode segment so that it separates adjacent electrode segments, thereby preventing short-circuiting therebetween, permitting easy fabrication of the transducer and improving the yield rate of fabrication.

Method for the manufacture of surface acoustic wave transducer

A surface acoustic wave convolver includes first and second interdigital electrodes for exciting surface acoustic waves and an output electrode for detecting the surface acoustic waves to extract a convolution output as an electrical signal, the first and second interdigital electrodes and the output electrode being formed on a piezoelectric or electrostrictive substrate. In order to improve convolution efficiency and obtain wide-range characteristics, each of the first and second interdigital electrodes has a predetermined thickness, the first interdigital electrode is arranged such that positive and negative electrodes are alternately arranged so as to have electrode widths and periods which are gradually decreased toward the output electrode, the second interdigital electrode is arranged such that positive and negative electrodes are alternately arranged so as to have electrode widths and periods which are gradually increased toward the output electrode, and the second interdigital electrode has a double electrode structure in addition, in order to reduce ripples in frequency characteristics, the output electrode are divided into a plurality of pieces, and two end portion of each of the first and second interdigital electrodes are weighted.

Surface acoustic wave convolver

In a surface acoustic wave transducer including a substrate made of a piezoelectric material, an input side IDT structure having positive and negative electrodes arranged in an interdigit manner and floating electrodes arranged between successive positive and negative electrodes, and an output side IDT structure having positive and negative electrodes arranged in an interdigit manner and floating electrodes arranged between successive positive and negative electrodes, the electrodes of the input and output side IDT structures are arranged such that a surface acoustic wave propagates in one direction, distances between corresponding tracks in the input and output side IDT structures are linearly changed and lengths of these tracks are changed in accordance with a predetermined window function.

Surface acoustic wave unidirectional transducer having floating

A surface acoustic wave filter device includes a substrate which comprises quartz or the like piezoelectric having a small temperature coefficient and which is formed with unidirectional transducers of asymmetrical construction. A floating electrode is spaced from intermediate position between adjacent positive and negative electrodes which are arranged in interdigital manner, to effectively utilize a mechanical reflection caused by the floating electrode. In consideration of the sign and magnitude of the reflection factor of the floating electrodes, short-circuited electrodes only are used for the floating electrodes. The surface acoustic wave filter device has improved temperature characteristic, insertion loss characteristic and phase characteristic.

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Sendai, Japan

Kazuhiko Yamanouchi