Interdigitated Electrodes Patents (Class 310/313B)
  • Patent number: 6166611
    Abstract: A resonator ladder type surface acoustic wave filter, has an input electrical terminal, an output electrical terminal, and a grounding terminal being formed on a piezoelectric substrate, a series arm surface acoustic wave resonator and a parallel arm surface acoustic wave resonator, each constructed from an interdigital transducer for exciting a surface acoustic wave, being formed between said input electrical terminal and said output electrical terminal, and when the center frequency of said resonator ladder type surface acoustic wave filter is denoted by fc, and capacitance determined by the number of electrode finger pairs and electrode finger overlap width in said interdigital transducer of said parallel arm surface acoustic wave resonator is denoted by Cp (fc: center frequency [GHz], Cp: capacitance of the interdigital transducer of the parallel arm surface acoustic wave resonator), capacitance C of multiples of said parallel arm surface acoustic wave resonator, connected to the same node between said in
    Type: Grant
    Filed: April 9, 1998
    Date of Patent: December 26, 2000
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Shun-ichi Seki, Yutaka Taguchi, Keiji Onishi, Osamu Kawasaki, Kazuo Eda
  • Patent number: 6160339
    Abstract: To provide a two-port SAW resonator in which spurious responses causes by higher-order vertical inharmonic modes are suppressed, a pair of reflectors and three IDTs are provided on the surface of a piezoelectric plate. The frequency-increase rate of the second and third IDTs is set to be smaller than that of the first IDT so that the frequency-increase rate of the first IDT is 2000 to 12000 ppm. In addition, by setting the number of pairs of the electrodes of the second and third IDTs at 2.75 to 3.75 or a quarter of the number of pairs of the electrodes of all the IDTs, spurious responses caused by higher-order vertical inharmonic modes are suppressed, and equivalent series resistance is reduced to approximately 20.OMEGA.. Therefore, a two-port SAW resonator having a superior frequency stability in a high-frequency band of 500 MHz or higher is realized.
    Type: Grant
    Filed: July 7, 1999
    Date of Patent: December 12, 2000
    Assignee: Seiko Epson Corporation
    Inventors: Michiaki Takagi, Takashi Yamazaki
  • Patent number: 6150900
    Abstract: A surface acoustic wave filter includes edge-reflection type surface acoustic wave resonators arranged as series and parallel arm resonators and connected in a ladder configuration. The edge-reflection type surface acoustic wave resonators defining the series and parallel arm resonators are disposed on a single common substrate and arranged so as to be substantially parallel to the end surface of the edge-reflection type surface acoustic wave resonators.
    Type: Grant
    Filed: May 11, 1999
    Date of Patent: November 21, 2000
    Assignee: Murata Manufacturing Co, Ltd
    Inventors: Michio Kadota, Hideya Horiuchi, Mamoru Ikeura
  • Patent number: 6150904
    Abstract: A surface acoustic wave filter includes a surface acoustic wave filter element and a package for holding the surface acoustic wave filter element. The surface acoustic wave filter element includes a plurality of series arm resonators and first, second and third parallel arm resonators each disposed on a piezoelectric substrate so as to define a ladder-type circuit. The first and second parallel arm resonators are close to input and output terminals of the filter element, respectively. Reference potential electrodes of the first and second parallel arm resonators are electrically connected to first and second electrode lands which are provided on the package and electrically isolated from each other while a reference potential electrode of the third parallel arm resonator is short-circuited with the reference potential electrode of either the first or second parallel arm resonator within the package.
    Type: Grant
    Filed: December 30, 1997
    Date of Patent: November 21, 2000
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Norio Taniguchi, Tadamasa Ushiroku
  • Patent number: 6147574
    Abstract: A unidirectional surface acoustic wave transducer includes a plurality of interdigital transducers and a plurality of reflectors disposed on a piezoelectric substrate. The directivity of a first group of the plurality of reflectors is opposite relative to the directivity of a second group of the plurality of reflectors.
    Type: Grant
    Filed: November 19, 1998
    Date of Patent: November 14, 2000
    Assignee: Murata Manufacturing Co., Ltd.
    Inventor: Hideo Kidoh
  • Patent number: 6127769
    Abstract: A surface acoustic wave device includes a surface acoustic wave substrate having first and second end surfaces, and a surface acoustic wave element provided on the surface acoustic wave substrate and operating using an SH-type surface acoustic wave. The surface acoustic wave element includes an interdigital transducer having a plurality of electrode fingers and a reflector having a plurality of electrode fingers. One of a pair of outermost electrode fingers is flush with one of the first and second end surfaces of the surface acoustic wave substrate, and the reflector is located at a side where the other of the pair of outermost electrode fingers is positioned, so that a SH-type surface acoustic wave excited by the IDT is confined between the reflector and the one of the first and second end surfaces.
    Type: Grant
    Filed: June 23, 1998
    Date of Patent: October 3, 2000
    Assignee: Murata Manufacturing Co. Ltd
    Inventors: Michio Kadota, Hideya Horiuchi, Mamoru Ikeura
  • Patent number: 6127904
    Abstract: A surface acoustic wave filter device suitable for CDMA communication system includes a piezoelectric substrate, and a unidirectional input side transducer and a bidirectional output side transducer are formed on the substrate. The filter device has satisfactory filtering characteristics in terms of insertion loss, frequency characteristic, T.T.E. attenuation level, group delay time, etc.
    Type: Grant
    Filed: November 30, 1998
    Date of Patent: October 3, 2000
    Assignee: NGK Insulators, Ltd.
    Inventors: Mitsuhiro Tanaka, Susumu Nomoto, Masahiko Sugiyama, Kenji Suzuki
  • Patent number: 6121859
    Abstract: A surface acoustic wave filter is formed by arranging electrode portions, each obtained by interdigitally forming a pair of comb electrodes on a piezoelectric substrate to oppose each other at a predetermined distance, on input and output sides, respectively. Each electrode portion includes an impedance matching circuit.
    Type: Grant
    Filed: March 18, 1999
    Date of Patent: September 19, 2000
    Assignee: NEC Corporation
    Inventor: Satoshi Takahashi
  • Patent number: 6114926
    Abstract: A piezoelectric substrate having two reflectors along a propagation path of a surface acoustic wave and three interdigital electrodes provided on said piezoelectric substrate consecutively between the reflectors. A primary side electrode is connected to an input/output terminal and a secondary side electrode is connected to a second input/output terminal. Each interdigital electrode includes include pairs of electrode fingers, where the pair of electrodes for one interdigital electrode is different than a pair of electrodes for another interdigital electrode.
    Type: Grant
    Filed: July 30, 1999
    Date of Patent: September 5, 2000
    Assignee: Fujitsu Limited
    Inventors: Masanori Ueda, Gou Endoh, Osamu Kawachi, Yoshiro Fujiwara
  • Patent number: 6111481
    Abstract: A double-mode surface-acoustic device having a piezoelectric substrate with two reflectors placed on the piezoelectric substrate and first through third interdigital electrodes placed on the substrate consecutively between the two reflectors. Each electrode containing first through third number of pairs of electrode fingers, respectively.
    Type: Grant
    Filed: July 30, 1999
    Date of Patent: August 29, 2000
    Assignee: Fujitsu Limited
    Inventors: Masanori Ueda, Gou Endoh, Osamu Kawachi, Yoshiro Fujiwara
  • Patent number: 6107899
    Abstract: A high-frequency surface acoustic wave filter is such that a plurality of comb electrodes are formed on a piezoelectric substrate, and said high-frequency surface acoustic wave filter has:said piezoelectric substrate;an input terminal;an output terminal; andat least two ground terminals provided on said piezoelectric substrate,wherein said ground terminals are neither connected on said piezoelectric substrate nor connected in a package containing said piezoelectric substrate.
    Type: Grant
    Filed: October 21, 1997
    Date of Patent: August 22, 2000
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Yutaka Taguchi, Kazuo Eda, Keiji Onishi, Shunichi Seki
  • Patent number: 6087756
    Abstract: A surface acoustic wave device substantially eliminates a stress caused by a curing shrinkage of an adhesive and substantially eliminates a strain in a case containing a surface acoustic wave element to prevent variation in characteristics of the surface acoustic wave device. In addition, a strength of joining of bonding wires provided in the surface acoustic wave device is improved to have an improved reliability. The surface acoustic wave element of the surface acoustic wave device is fixed on a case member via a soft adhesive and bonding electrodes of the surface acoustic wave element have a plurality of through holes. Ends of the bonding wires are wire-bonded to the bonding electrodes having the through holes formed therein.
    Type: Grant
    Filed: August 4, 1998
    Date of Patent: July 11, 2000
    Assignee: Murata Manufacturing Co., Ltd.
    Inventor: Makoto Shibutani
  • Patent number: 6084503
    Abstract: Radio-interrogated surface-wave technology sensor, in which the sensitive element (12) is an impedance which is electrically connected as termination to a surface-wave structure (26) of the sensor.
    Type: Grant
    Filed: October 17, 1997
    Date of Patent: July 4, 2000
    Assignee: Siemens Aktiengesellschaft
    Inventors: Werner Ruile, Gerd Scholl, Thomas Ostertag, Leonhard Reindl, Valentin Magori
  • Patent number: 6078229
    Abstract: It is an object on the invention to provide a SAW device sealed by resin, which is low priced and suited for decreasing its thickness and weight and requires no particular course for processing a substrate, and a method for fabricating the same. A functional surface of a piezoelectric substrate provided with interdigtal transducers and a mounting surface of a circuit substrate are opposed to each other to form vibration cavities for surface wave propagation areas therebetween. Electrical power is supplied to the piezoelectric substrate from the circuit substrate via electrode pads formed on respective inner surface of both the substrate and bumps inserted therebetween. A resin film adheres to the respective inner surfaces of both the substrates except the surface wave propagation areas to shield the vibration cavity from the environmental space. Apertures are previously formed at predetermined parts of the resin film by means of a laser.
    Type: Grant
    Filed: August 4, 1998
    Date of Patent: June 20, 2000
    Assignee: NEC Corporation
    Inventors: Yoshitsugu Funada, Michinobu Tanioka
  • Patent number: 6075426
    Abstract: A surface acoustic wave device includes a piezoelectric substrate and plural IDTs for sending and receiving SAW mounted on the substrate. At least one of the IDTs includes a positive electrode including plural positive split electrodes (PSEs) and a negative electrode including plural negative split electrodes (NSEs). The PSEs and NSEs are arranged alternately. Each of the PSEs andNSEs has apair of electrode fingers. Two electrode fingers of each of the split electrodes are different in width in a direction in which a SAW is excited. An angle .alpha. determined by a direction transverse to the electrode fingers from one of the two electrode fingers having a smaller reflection factor toward the other one having a larger reflection factor and a direction in which the SAW excited by the IDT including the split electrodes travels to one of the IDTs for receiving the SAW is equal to or larger than 0.degree. and smaller than 90.degree., i.e., 0.ltoreq..alpha.<90.
    Type: Grant
    Filed: September 15, 1998
    Date of Patent: June 13, 2000
    Assignee: Fujitsu Limited
    Inventors: Jun Tsutsumi, Takashi Matsuda, Osamu Ikata, Yoshio Satoh
  • Patent number: 6072377
    Abstract: A surface acoustic wave device includes a piezoelectric substrate, and comb-shaped electrodes each having a bus bar and a plurality of electrode fingers disposed on the piezoelectric substrate. At least one of the fingers and the bus bar are connected to each other via at least two different connecting portions at two different locations.
    Type: Grant
    Filed: February 1, 1999
    Date of Patent: June 6, 2000
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Toshiyuki Tajima, Kunio Minami, Kenji Sakaguchi
  • Patent number: 6072263
    Abstract: A surface acoustic wave position-sensing device comprising a piezoelectric substrate, a nonpiezoelectric plate and an interdigital transducer formed on one end surface of the piezoelectric substrate. The piezoelectric substrate is mounted on an upper end surface of the nonpiezoelectric plate through the interdigital transducer. When using the surface acoustic wave transducing device as an input device, an electric signal is applied to the interdigital transducer. In this time, a surface acoustic wave is excited in the piezoelectric substrate, and then transmitted to the upper end surface of the nonpiezoelectric plate. When using the surface acoustic wave transducing device as an output device, a surface acoustic wave transmitted from the upper end surface of the nonpiezoelectric plate to the piezoelectric substrate is transduced to an electric signal at the interdigital transducer.
    Type: Grant
    Filed: August 9, 1996
    Date of Patent: June 6, 2000
    Inventor: Kohji Toda
  • Patent number: 6060812
    Abstract: An ultrasonic touch-position sensing device comprising a piezoelectric substrate, an input interdigital transducer T formed at the middle of a lower end surface of the piezoelectric substrate, four output interdigital transducers R.sub.1, R.sub.2, R.sub.3 and R.sub.4, a nonpiezoelectric plate, and a signal controller connected with output terminals of the output interdigital transducers. The interdigital transducers R.sub.1 and R.sub.2, are formed at one edge of the lower end surface of the piezoelectric substrate, and the interdigital transducers R.sub.3 and R.sub.4, are formed at the other edge thereof. Each output interdigital transducer is placed such that the finger direction thereof is slanting to that of the interdigital transducer T. A lower end surface of the nonpiezoelectric plate is cemented on an upper end surface of the piezoelectric substrate, causing a bilayer assembly. An upper end surface of the nonpiezoelectric plate consists of four areas S.sub.1, S.sub.2, S.sub.3 and S.sub.4.
    Type: Grant
    Filed: August 1, 1997
    Date of Patent: May 9, 2000
    Inventor: Kohji Toda
  • Patent number: 6060964
    Abstract: The surface acoustic wave (SAW) filter has two or more identical acoustic tracks. The input side of the tracks is electrically connected in parallel and the output side is electrically connected in series, whereby the impedance of input side of the SAW filter is reduced relative to the impedance of the individual acoustic tracks.
    Type: Grant
    Filed: June 19, 1998
    Date of Patent: May 9, 2000
    Assignee: Siemens Matsushita Components GmbH & Co. KG
    Inventors: Thomas Baier, Jurgen Machui, Isidor Schropp, Gunter Muller
  • Patent number: 6057630
    Abstract: There is provided a surface acoustic wave device for use as a filter in a television receiver set which can reduce reflection waves generated from outermost electrodes of input and output interdigital transducers to improve various filter characteristics. In the surface acoustic wave device having, on a piezoelectric substrate, the input interdigital transducer for converting an electric signal into a surface acoustic wave and the output interdigital transducer, disposed to oppose the input interdigital transducer, for converting the surface acoustic wave resulting from the conversion by the input interdigital transducer into an electric signal, a first dummy electrode is provided to a first outermost electrode finger of the output interdigital transducer, the first outermost electrode finger being located at one end of the output interdigital transducer opposite to the input interdigital transducer, and having an electrode aperture length of .lambda.
    Type: Grant
    Filed: April 16, 1998
    Date of Patent: May 2, 2000
    Assignee: Hitachi Media Electronics Co., Ltd.
    Inventors: Hitoshi Yanagihara, Takashi Shiba, Katsumi Itoh, Akitsuna Yuhara
  • Patent number: 6051908
    Abstract: A relatively narrow fractional bandwidth saw filter formed on a standard ST cut of quartz. The electrode pattern is modified in order to eliminate distortion. In particular, the overlap pattern is formed with one or less active overlaps per wavelength in those regions of the SAW filter where the weighing function is maximum. A plurality of six finger/.lambda. electrode patterns with two active overlaps per wavelength is also provided.
    Type: Grant
    Filed: March 19, 1999
    Date of Patent: April 18, 2000
    Assignee: TRW Inc.
    Inventors: Edward M. Garber, Daniel K. Ko, David A. Slavin
  • Patent number: 6040651
    Abstract: A surface acoustic wave device includes a piezoelectric substrate, an input first interdigital electrode, and an output second interdigital electrode. The input first interdigital electrode is formed on the piezoelectric substrate. The output second interdigital electrode is formed on the piezoelectric substrate to be adjacent to the first interdigital electrode. A ratio of an overlap width to an aperture width of the first interdigital electrode and a ratio of an overlap width to an aperture width of the second interdigital electrode are set to different values, so that a transverse secondary mode is suppressed with one of the first and second interdigital electrodes while a transverse quaternary mode is suppressed with the other of the first and second interdigital electrodes.
    Type: Grant
    Filed: July 23, 1999
    Date of Patent: March 21, 2000
    Assignee: NEC Corporation
    Inventors: Susumu Yoshimoto, Yasushi Yamamoto
  • Patent number: 6037847
    Abstract: A surface acoustic wave device includes a piezoelectric substrate of a single crystal LiTaO.sub.3 and an electrode pattern provided on the piezoelectric substrate. The electrode pattern contains Al as a primary component and has a thickness in a range of 0.03-0.15 times a wavelength of a surface acoustic wave excited on the piezoelectric substrate. The piezoelectric substrate has an orientation rotated about an X-axis thereof from a Y-axis thereof toward a Z-axis thereof, with a rotational angle of 39-46.degree..
    Type: Grant
    Filed: October 7, 1996
    Date of Patent: March 14, 2000
    Assignee: Fujitsu Limited
    Inventors: Masanori Ueda, Osamu Kawachi, Gou Endoh, Osamu Ikata, Ken-ya Hashimoto, Masatsune Yamaguchi
  • Patent number: 6034578
    Abstract: A surface acoustic wave device which comprises: a plurality of interdigital transducers formed on a surface acoustic wave substrate; and a plurality of thin film electrodes disposed between the interdigital transducers and an end surface of the surface acoustic wave substrate and electrically independently of the interdigital transducers, at least one of distances between adjacent ones of the thin film electrodes being set to be smaller than a distance between the thin film electrodes and the interdigital transducers, so that the electrical performance of the device as well as the insulation resistance does not deteriorate, and the interdigital transducers can be prevented from being electrostatically broken.
    Type: Grant
    Filed: March 11, 1999
    Date of Patent: March 7, 2000
    Assignee: Hitachi Media Electronics Co., Ltd.
    Inventors: Yuji Fujita, Norio Hosaka, Misao Nakajima
  • Patent number: 6034577
    Abstract: A surface acoustic wave filter having one or a plurality of filter functional units each comprising a series arm resonator and a parallel arm resonator. Each of the series arm resonator and the parallel arm resonator is constituted by an interdigital transducer and grating reflectors formed on a piezoelectric substrate composed of 64.degree.-rotated Y-cut X-propagating LiNbO.sub.3. The series arm resonator is constructed by electrically connecting a one-port resonator in series with a signal line, and the parallel arm resonator is constructed by electrically connecting a one-port resonator in parallel with the signal line. In the interdigital transducer in the series arm resonator and/or the parallel arm resonator, one or more sets of electrode fingers continuously adjacent to each other are formed.
    Type: Grant
    Filed: September 22, 1998
    Date of Patent: March 7, 2000
    Assignee: Sanyo Electric Co., Ltd.
    Inventors: Kuniyuki Matsui, Yasuhiro Hirao, Yasumi Kobayashi, Kousuke Takeuchi, Kenichi Shibata
  • Patent number: 6031315
    Abstract: A quartz single crystal substrate (12), includes a prescribed range of Euler angles for substrate and crystal orientation which improves signal processing for surface acoustic wave (SAW) devices (10). When a voltage is applied to an input inter digital transducer (IDT) (16) of the SAW device (10), a surface acoustic wave is generated in the quartz substrate (12). The surface acoustic wave propagates in a direction generally perpendicular to electrodes (20) of the IDT (16). The quartz crystal cut and wave propagation directions are defined to reduce the adverse effects of diffraction on SAW devices (10). As a result, frequency response distortions and insertion loss increases due to diffraction are reduced while maintaining good temperature stability and a low power flow angle.
    Type: Grant
    Filed: July 15, 1998
    Date of Patent: February 29, 2000
    Assignee: Sawtek Inc.
    Inventor: Benjamin P. Abbott
  • Patent number: 6031435
    Abstract: In a multiple stage ladder type SAW filter constructed by cascade-connecting several SAW resonators in the form of a multiple-stage ladder, the electrode pitches of the first stage series-arm SAW resonator through the last stage series-arm SAW resonator, respectively, are gradually decreased. In this case, each stage has a series-arm SAW resonator and a shunt-arm SAW resonator. As a result, the resonance frequencies of the first stage series-arm SAW resonator through the last stage series-arm SAW resonator are increased monotonically from the first stage to the last stage. As a consequence, the frequencies of the upper poles of attenuation generated by the series-arm SAW resonators differ from each other. Therefore, a desired amount of attenuation can be obtained over a wide band.
    Type: Grant
    Filed: January 29, 1999
    Date of Patent: February 29, 2000
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Naoto Inose, Hok Huor Ou
  • Patent number: 6023122
    Abstract: A SAW device has tapered trasnsducers each of which is divided into two or more tapered transducer parts, which are arranged in line with one another in one or more SAW tracks with the tapers of adjacent tapered transducer parts complementary to one another to provide a compact arrangement. The tapered transducer parts can be symmetrically or asymmetrically tapered to provide different frequency bands for band or bandwidth switching of the SAW device. Input and output impedances of the SAW device can be maintained during such switching by switching of dummy transducer parts also provided on the same piezoelectric substrate.
    Type: Grant
    Filed: April 15, 1999
    Date of Patent: February 8, 2000
    Assignee: Nortel Networks Corporation
    Inventors: Wen Liu, Thomas P. Cameron, Steve A. Beaudin
  • Patent number: 6023204
    Abstract: A surface acoustic wave device includes a plurality of surface acoustic wave filter chips having external connection terminals and a package accommodating the plural surface acoustic wave filter chips. The package is provided with a plurality of terminals for connection with the surface acoustic wave filter chips, and one of the external connection terminals of a first one of the surface acoustic wave filter chips is connected with one of the terminals of the package via a second one of the surface acoustic wave filter chips.
    Type: Grant
    Filed: September 15, 1998
    Date of Patent: February 8, 2000
    Assignee: Fujitsu Limited
    Inventors: Osamu Ikata, Yoshio Satoh, Takashi Matsuda, Jun Tsutsumi, Satoshi Miyamoto
  • Patent number: 6020672
    Abstract: A surface acoustic wave converter for converting an electric signal into a surface acoustic wave includes an interdigital transducer provided on a piezoelectric substrate. The interdigital transducer has first and second electrode groups each having one or more electrode fingers to which a first signal is almost simultaneously inputted. The surface acoustic wave converters includes first input unit for inputting the first signal to the one or more electrode fingers of the first electrode group, and second input unit for inputting the first signal to the one or more electrode fingers of the second electrode group when at least one of surface acoustic waves excited by the first signal in the one or more electrode fingers of the first electrode group reaches one of the one or more electrode fingers of the second electrode group.
    Type: Grant
    Filed: September 26, 1996
    Date of Patent: February 1, 2000
    Assignee: Canon Kabushiki Kaisha
    Inventors: Akane Yokota, Akira Torisawa, Koichi Egara, Tadashi Eguchi, Akihiro Koyama, Takahiro Hachisu
  • Patent number: 6011344
    Abstract: The transducer according to the invention, driven in differential mode, consists of at least a first transducer (5) and a second transducer (6) which are connected in parallel so as to obtain the symmetry of the differential inputs, respectively forming a first and a second acoustic channel; the two transducers (5, 6) exhibiting a specified longitudinal offset with respect to one another. Applications: mobile radio filters.
    Type: Grant
    Filed: June 4, 1998
    Date of Patent: January 4, 2000
    Assignee: Thomson-CSF
    Inventors: Pierre Dufilie, Marc Solal
  • Patent number: 6005326
    Abstract: A surface acoustic wave device includes a piezoelectric substrate, an input first interdigital electrode, and an output second interdigital electrode. The input first interdigital electrode is formed on the piezoelectric substrate. The output second interdigital electrode is formed on the piezoelectric substrate to be adjacent to the first interdigital electrode. A ratio of an overlap width to an aperture width of the first interdigital electrode and a ratio of an overlap width to an aperture width of the second interdigital electrode are set to different values, so that a transverse secondary mode is suppressed with one of the first and second interdigital electrodes while a transverse quaternary mode is suppressed with the other of the first and second interdigital electrodes.
    Type: Grant
    Filed: October 9, 1997
    Date of Patent: December 21, 1999
    Assignee: NEC Corporation
    Inventors: Susumu Yoshimoto, Yasushi Yamamoto
  • Patent number: 5999068
    Abstract: A surface acoustic wave filter of multi-stage connection type including a plurality of surface acoustic wave filters formed on a piezoelectric substrate and a connection section for electrically connecting the surface acoustic wave filters in a cascade connection. Each of the surface acoustic wave filters includes interdigital transducers with two signal terminals for electric input and output, each interdigital transducer including an excitation section for exciting a surface acoustic wave and two terminal sections disposed on opposite sides of the excitation section, the two terminal sections serving as input or output terminal for electric signal and ground terminal. One of the signal terminal sections is connected to the connection section, and an electrode area of said one of the signal terminal sections is adjusted so that a parasitic capacitance formed between said one of the signal terminal sections and a grounding point of the surface acoustic wave filter is less than or equal to 0.01 pF.
    Type: Grant
    Filed: March 13, 1998
    Date of Patent: December 7, 1999
    Assignee: Fujitsu Limited
    Inventors: Jun Tsutsumi, Osamu Ikata, Yoshio Satoh
  • Patent number: 5990762
    Abstract: A surface acoustic wave resonator is constituted by an IDT electrode and reflector electrodes disposed on both sides thereof, on a piezoelectric substrate. Two of said surface acoustic wave resonators are disposed nearby so that the propagation directions of the respective surface acoustic waves are in parallel to each other to make acoustic couple to constitute a surface acoustic wave filter having plural exciting modes with different propagation frequencies. The bus bar electrodes of each of two IDT electrodes are electrically separated from each other, and the leading out electrodes led out from at least two spots on those bus bar electrodes are electrically connected to each other, by which one side of the balanced input and output terminal. As a result, the electrode resistance of the IDT electrode is alleviated to make the insertion loss less.
    Type: Grant
    Filed: May 23, 1997
    Date of Patent: November 23, 1999
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroyuki Nakamura, Toru Yamada, Kazunori Nishimura, Toshio Ishizaki
  • Patent number: 5986523
    Abstract: 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.
    Type: Grant
    Filed: August 10, 1998
    Date of Patent: November 16, 1999
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Kazuhiko Morozumi, Haruo Morii, Michio Kadota
  • Patent number: 5977686
    Abstract: 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.
    Type: Grant
    Filed: January 15, 1998
    Date of Patent: November 2, 1999
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Michio Kadota, Kazuhiko Morozumi, Haruo Morii
  • Patent number: 5977846
    Abstract: The inside-band characteristic of an internal reflection type unidirectional surface acoustic wave filter is improved by using an internal reflection type unidirectional surface acoustic wave filter having positive and negative finger electrodes (10, 11) of the interdigital transducer and having open or short-circuit type floating electrodes (12) therebetween. The finger electrodes are subjected to weighting by a withdrawal technique and the filter is structured such that at portions wherein no electrical cross is made between the positive and negative finger electrodes, i.e., in case where adjacent finger electrodes each have the same sign as that of the positive finger electrode or negative finger electrode, the floating electrodes (13) located therebetween are not displaced from the center positions therebetween.
    Type: Grant
    Filed: October 29, 1997
    Date of Patent: November 2, 1999
    Assignee: NEC Corporation
    Inventors: Ryuji Kajihara, Yasushi Yamamoto
  • Patent number: 5973438
    Abstract: An ultrasonic switching device comprising a piezoelectric substrate, an input- and an output interdigital transducers formed on an upper end surface of the piezoelectric substrate, and a nonpiezoelectric plate, a lower end surface of the nonpiezoelectric plate being cemented on the upper end surface of the piezoelectric substrate. The output interdigital transducer has a finger-overlap zone R.sub.i (i=1), or has N finger-overlap zones R.sub.i (i=1, 2, . . . , N) and N-1 finger-overlap zones Q.sub.i {i=1, 2, . . . , (N-1)} between two finger-overlap zones R.sub.i and R.sub.(i+1). Each finger-overlap zone R.sub.i comprises three zones R.sub.ia, R.sub.ib and R.sub.im. The finger direction of the zones R.sub.ia and R.sub.ib runs parallel with that of the input interdigital transducer. The finger direction of the zone R.sub.im is slanting to that of the input interdigital transducer by an angle .alpha.. The finger direction of the finger-overlap zone Q.sub.
    Type: Grant
    Filed: February 13, 1998
    Date of Patent: October 26, 1999
    Inventor: Kohji Toda
  • Patent number: 5966060
    Abstract: A surface acoustic wave apparatus includes first and second longitudinally-coupled resonator filters disposed on a surface-wave board. In each longitudinally-coupled resonator filter, the ground electrodes of IDTs disposed at opposite sides of the center IDT and adjacent to reflectors are connected to different ground electrodes located on the same layer in the package, with at least two bonding wires.
    Type: Grant
    Filed: September 16, 1997
    Date of Patent: October 12, 1999
    Assignee: Murata Manufacturing Co., Ltd.
    Inventor: Katsuhiro Ikada
  • Patent number: 5955933
    Abstract: In a surface acoustic wave filter constituted with a ladder of resonators having a resonance frequency or an anti-resonance frequency, an input current flowing into a resonator in a parallel arm at the first stage from the input is so large as to deteriorate its lifetime caused from a heat generation by the resistance of the thin film wiring. As a measure to this problem, bonding wires (30, 31) connected onto points on connection electrodes (130, 131) for connecting an end of each of plural comb teeth electrodes 111 forming the resonators R.sub.s1 & R.sub.p1, or on a lead conductor (130-1) extended longitudinally from the connection electrode, are allotted at both sides of a center line (C1) of the plural comb teeth electrode group. Furthermore, a bonding wire may be connected substantially onto the center line C1 as well. It is preferable for the bonding wires to be located substantially symmetric with respect to the center line C1.
    Type: Grant
    Filed: May 15, 1996
    Date of Patent: September 21, 1999
    Assignee: Fujitsu Limited
    Inventors: Tokihiro Nishihara, Yoshio Satoh, Hidema Uchishiba, Takashi Matsuda, Osamu Ikata
  • Patent number: 5952765
    Abstract: A relatively narrow fractional bandwidth saw filter formed on a standard ST cut of quartz. The electrode pattern is modified in order to eliminate distortion. In particular, the overlap pattern is formed with one or less active overlaps per wavelength in those regions of the SAW filter where the weighing function is maximum. A plurality of six finger/.lambda. electrode patterns with two active overlaps per wavelength is also provided.
    Type: Grant
    Filed: November 26, 1996
    Date of Patent: September 14, 1999
    Assignee: TRW Inc.
    Inventors: Edward M. Garber, Daniel K. Ko, David A. Slavin
  • Patent number: 5952899
    Abstract: A ladder filter includes a plurality of series arm resonators and a plurality of parallel arm resonators. The series arm resonators are connected in series to form a series arm of a ladder circuit and are located at a first integrated region. Each series arm resonator includes an edge-reflection surface acoustic wave (SAW) resonator which has a piezoelectric material portion and a pair of edges thereof and utilizes a shear horizontal surface acoustic wave to be excited on the piezoelectric material portion. Each of the parallel arm resonators is connected in parallel between the series arm and a ground potential to form a parallel arm of a ladder circuit. Each of the parallel arm resonators includes an edge reflection SAW resonator which has a piezoelectric material portion with a pair of edges thereof and utilizes a shear horizontal surface acoustic wave to be excited on the piezoelectric material portion.
    Type: Grant
    Filed: May 12, 1998
    Date of Patent: September 14, 1999
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Michio Kadota, Takeshi Nadota, Toshimaro Yoneda, Junya Ago
  • Patent number: 5936487
    Abstract: The disclosure relates to differential input/output surface acoustic wave devices with proximity coupling. The disclosed device comprises a whole number N of acoustic channels, where N is at least equal to two. The acoustic channels are coupled together by proximity. A first acoustic channel comprises at least one transducer separated into several parts electrically connected in parallel with one another to form a first differential port (E+) and a second differential port (E-). The polarities of the different parts of the transducer are chosen so that the first differential port (E+) and the second differential port (E-) are electrically symmetrical. Application in particular to surface acoustic wave filters for portable telephones.
    Type: Grant
    Filed: April 9, 1998
    Date of Patent: August 10, 1999
    Assignee: Thomson-CSF
    Inventors: Marc Solal, Pierre Dufilie
  • Patent number: 5933062
    Abstract: An acoustic wave ladder filter (30) with lossy inductances (42) connected in parallel with resonators (40). Shunt sections (36,37) of the ladder filter (30) include impedance inverters having pass frequencies within the stopband of series resonators (33,34,35). The filter (30) additionally includes variable capacitors (44) connected in parallel with the inductances (42) to provide adjustment capabilities. The use of lossy inductances (42) actually increases effective coupling coefficient of the filter (30) and improves insertion loss thereby allowing improved design flexibility.
    Type: Grant
    Filed: November 4, 1997
    Date of Patent: August 3, 1999
    Assignee: Motorola Inc.
    Inventor: Richard S. Kommrusch
  • Patent number: 5932950
    Abstract: A SAW resonator disposed with an IDT electrode and reflector electrodes is formed on the surface of a piezoelectric substrate. Three pieces of the SAW resonator form an acoustic coupling by being disposed close to each other, electrode fingers comprising the IDT electrode in the center are all grounded, and IDT electrode fingers are electrically independent on the side to be connected to input-output terminals of the IDT electrodes disposed outside. As a result, three excitation modes having different propagation frequencies are generated which are used to attain a broad band SAW resonator filter. When these three pairs of the IDT electrode are electrically independent, a balanced input-output can be achieved, and excellent out-of-band rejection characteristics can be obtained.
    Type: Grant
    Filed: August 6, 1996
    Date of Patent: August 3, 1999
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Toru Yamada, Toshio Ishizaki, Kazunori Nishimura, Kozo Murakami
  • Patent number: 5925967
    Abstract: An ultrasonic switching device comprises a piezoelectric substrate, and an input- and an output interdigital transducers formed on an upper end surface of the piezoelectric substrate. The output interdigital transducer has a finger-overlap zone R.sub.i (i=1), or has N finger-overlap zones R.sub.i (i=1, 2, . . . , N) and N-1 finger-overlap zones Q.sub.i {i=1, 2, . . . , (N-1)} between two finger-overlap zones R.sub.i and R.sub.(i+1). Each finger-overlap zone R.sub.i comprises zones R.sub.ia, R.sub.ib and R.sub.im. The finger direction of the zones R.sub.ia and R.sub.ib runs parallel with that of the input interdigital transducer. The finger direction of the zone R.sub.im is slanting to that of the input interdigital transducer by an angle .alpha.. The finger direction of the finger-overlap zone Q.sub.i is slanting to that of the input interdigital transducer by an angle .+-..beta..
    Type: Grant
    Filed: February 13, 1998
    Date of Patent: July 20, 1999
    Inventor: Kohji Toda
  • Patent number: 5923231
    Abstract: In a surface acoustic wave device for processing signals of relatively high frequencies, as of above 1 GHz, by the use of surface acoustic waves which propagate on the surface of a piezoelectric substrate, radiating bulk waves in the direction of depth of the piezoelectric substrate, an IDT structure is provided, which does not increase propagation loss and has sufficiently low electric resistance. The device comprises a piezoelectric substrate 10, and an electrode of a conducting film 12 for exciting, receiving, reflecting and/or propagating surface acoustic waves, and the surface acoustic waves propagate on the surface of the piezoelectric substrate, radiating at least one transverse component of bulk waves in the direction of depth of the piezoelectric substrate 10.
    Type: Grant
    Filed: September 13, 1996
    Date of Patent: July 13, 1999
    Assignee: Kinseki Limited
    Inventors: Yukio Ohkubo, Takahiro Sato
  • Patent number: 5914554
    Abstract: An end-face reflecting-type surface wave resonator using the SH-type surface wave achieves two types of resonance characteristics by use of only a single device. An interdigital transducer having a pair of comb-like electrodes are formed on a piezoelectric substrate having two oppositely-facing end faces. The interdigital transducer has two peaks of main lobes and are assigned with weights so that the two peaks of main lobes substantially coincide with frequency positions of attenuation poles disposed across a main lobe of a virtual normal-type interdigital transducer having the same number of pairs of electrodes as the weighted interdigital transducer. Thus, two types of resonance characteristics can be obtained.
    Type: Grant
    Filed: August 30, 1996
    Date of Patent: June 22, 1999
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Michio Kadota, Junya Ago
  • Patent number: 5914645
    Abstract: 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.
    Type: Grant
    Filed: June 4, 1997
    Date of Patent: June 22, 1999
    Assignee: Sanyo Electric Co., Ltd.
    Inventors: Yasumi Kobayashi, Kuniyuki Matsui, Naoki Tanaka, Hiroshi Okano, Tatsuro Usuki, Kenichi Shibata
  • Patent number: 5909157
    Abstract: A surface acoustic wave filter device suitable for CDMA communication system, includes a piezoelectric substrate, and a unidirectional input side transducer and a bidirectional output side transducer are formed on the substrate. The filter device has satisfactory filtering characteristics in terms of insertion loss, frequency characteristic, T.T.E. attenuation level, group delay time, etc.
    Type: Grant
    Filed: April 24, 1997
    Date of Patent: June 1, 1999
    Assignee: NGK Insulators, Ltd.
    Inventors: Mitsuhiro Tanaka, Susumu Nomoto, Masahiko Sugiyama, Kenji Suzuki