Sanyo Electric Co., Ltd.

Naoki Tanaka

Tatsuro Usuki

Morio Ogura

Kenichi Shibata

Hiroshi Okano

Yasumi Kobayashi

Masami Ikeda

Kuniyuki Matsui

Toshio Tanuma

Kazuya Niki

Yusuke Takahashi

Fumio Kameoka

Kouichi Yoshioka

Tatsurou Usuki

Hideki Itou

A surface acoustic wave device including an electrode formed from an electrode material represented by the composition formula MVwherein M is aluminum or an aluminum-copper alloy, V is vanadium, x+y=100 and 0.10&#x2266;y&#x3c;0.2. The device is excellent in durability against applying electric power and diminished in internal resistance.

Surface acoustic wave device

The present invention provides an unbalanced input and balanced output type SAW filter capable of obtaining stop-band attenuation approximately equivalent to that of an unbalanced input and unbalanced output type SAW filter. IDTs ( ) ( ) are respectively disposed on each side of a middle IDT ( ). A comb electrode ( ) of the middle IDT ( ) is connected with an input terminal (In) and other comb electrode ( ) is grounded. A comb electrode ( ) of the IDT ( ) and a comb electrode ( ) of the IDT ( ) are respectively connected with output terminals (Out ) and (Out ), and other comb electrode ( ) of the IDT ( ) and other comb electrode ( ) of the IDT ( ) are connected to each other and grounded. Electrode fingers ( ), ( ), ( ) of the middle IDT ( ) and the side IDT ( ), ( ) are so arranged that adjacent electrode fingers of the middle IDT and the IDT on one side make a connection between terminals and the other adjacent electrode fingers of the middle IDT and the IDT on other side make a connection between a terminal and a ground.

Longitudinal coupled multiple mode surface acoustic wave filter

In the surface acoustic wave filter, a longitudinally-coupled double-mode resonator filter formed by arranging a plurality of inter-digital transducers for exciting and receiving a surface acoustic wave adjacent each other in the direction of propagation of the surface acoustic wave is connected in series to a resonator having one or a plurality of inter-digital transducers for exciting and receiving a surface acoustic wave. A cutoff frequency on the high-frequency side of the pass band of the longitudinally-coupled double-mode resonator filter and the antiresonant frequency of the resonator are substantially equal. In the surface acoustic wave filter, the sharpness in the vicinity of the cutoff frequency on the high-frequency side of the pass band is high, sufficient attenuation can be obtained, and the input and output impedance matching state is good.

Surface acoustic wave filter

An SAW device substrate and an SAW device having a larger value of K than conventional SAW device substrates can be obtained by using LiNbO represented by Eulerian angles of (18-30&deg;, 80-100&deg;, 35-75&deg;) and determining the thickness H of a piezoelectric substrate and the pitch &lgr; of electrodes so that KH is at least 2.3 and at most 4.5. Alternatively, an Li B O layer is formed as a piezoelectric substrate on a surface of a glass layer to obtain an Li B O /glass structured SAW device substrate. More preferably, such Li B O that is represented by Eulerian angles of (0-45&deg;, 85-95&deg;, 85-95&deg;) is employed. Furthermore, the SAW device substrate is used to form an SAW device so that the KH parameter is about 0.5.

Substrate for surface acoustic wave device and surface acoustic wave device

An SAW device includes a glass substrate, an LiNbO,(LN) substrate, and an electrode. When a pitch of the electrode is &lgr;, a thickness of the LN substrate is H, and K equals to 2&pgr;/&lgr;, a product of K and H is at least 0.5 and at most 1.0. Accordingly, an SAW device is obtained which is provided with high K,and an enhanced temperature characteristic and which can be advantageously reduced in size.

An SAW device including a glass substrate, an LiNbO,(LT) substrate, and an electrode. When a pitch of the electrode is &lgr;, a thickness of the LT substrate is H, and K equals to 2&pgr;/&lgr;, a product of K and H is at least 0.5 and at most 1.5. Accordingly, a SAW device which can advantageously reduced in size by a reduction in propagation velocity and which is provided with high K,and an enhanced temperature characteristic as having a good temperature characteristic of the LT substrate.

An SAW device including a glass substrate, an LiNbO,(LN) substrate, and an electrode. When a pitch of the electrode is &lgr;, a thickness of the LN substrate is H, and K equals to 2&pgr;/&lgr;, a product of K and H is at least 1.6 and at most 1.8. Accordingly, a SAW device which can advantageously reduced in size and provided with an enhanced temperature characteristic is obtained while ensuring high K,.

A surface acoustic wave filter of the transversely coupled mode resonator type including an interdigital electrode,having a plurality of electrode digits, and two reflectors,arranged, respectively, at opposite sides of the interdigital electrode,at a distance C from the electrode and each having a plurality of electrode digits. The filter has a pitch ratio of A/B, where A is the digit pitch of the interdigital electrode,and B is the digit pitch of each of the reflectors,The pitch ratio A/B and the distance C are determined such that on a two-dimensional coordinate system (X, Y) where the pitch ratio A/B is plotted as the Y-axis and a value C/&lgr; obtained by dividing the distance C by the wavelength &lgr; of surface acoustic waves is plotted as the X-axis, the pitch ratio A/B and the distance C are contained in a quadrilateral region having vertices at four points, i.e., point a (0.55, 0.983), point b (0.70, 1.010), point c (0.85, 1.010) and point d (0.85, 1.007), whereby the filter can be made more compact and is improved in characteristics outside the pass band.

Surface acoustic wave filters with cascaded transversely coupled mode resonator filters

A surface acoustic wave device including, as formed on a piezoelectric substrate, one or a plurality of resonators connected together, each of the resonators comprising an interdigital transducer and a grating reflector, the object of the invention is to compact the device by improving the reflection efficiency of the grating reflector. When the grating reflector is a metal strip array reflector of the open type, the grating reflector has an electrode occupancy ratio of 0.7 to 0.8. Alternatively, when a metal strip array reflector of the short-circuit type is used, the grating reflector has an electrode occupancy ratio of 0.45 to 0.55, or when a metal strip array reflector of the interdigital type is used, the grating reflector has an electrode occupancy ratio of 0.7 to 0.85.

In a surface acoustic wave device comprising a substrate of lithium tantalate or lithium niobate, and interdigital electrodes formed on the substrate and made of a thin film consisting primarily of aluminum, the interdigital electrodes are optimized in the ratio of the thickness of the film to the period of a plurality of electrode digits connected to a common terminal with propagation loss taken as an objective function. The ratio is set in the range of 0.03 to 0.10 to ensure a lower propagation loss than in the prior art.

Surface acoustic wave device with optimized ratio of film thickness to

A surface acoustic wave device adapted to attain a higher acoustic velocity than conventionally by realizing SH waves excitable at a higher frequency than the fundametal mode of Rayleigh waves. Aluminum is sputtered for deposition on the R-plane of a sapphire substrate 1 using a sputter ion source, and at the same time, the R-plane of the substrate 1 is irradiated with a nitrogen ion beam having energy of 50 to 250 eV at a current density of 0.2 to 1.0 mA/cm.sup.2 using an assist ion source to form an aluminum nitride thin film 2 on the R-plane of the substrate 1 with the [00.1] axis of the film tilted with respect to a normal to the substrate.

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Sakai, Japan

Naoki Tanaka