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US 5,932,950 AGranted
Surface acoustic wave filter
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsToru Yamada, Toshio Ishizaki, Kazunori Nishimura, Kozo Murakami
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AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsToru Yamada, Toshio Ishizaki, Kazunori Nishimura, Kozo Murakami
Estimating the term…
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.
A surface acoustic wave (SAW) filter comprising a SAW resonator disposed on a surface of a piezoelectric substrate, the SAW resonator comprising at least three pieces, an inter-digital transducer (IDT) electrode having at least four sides disposed in the center of the SAW filter and reflectors disposed adjacent to two sides of the IDT electrode, wherein said SAW resonator form an acoustic coupling by disposing the at least three pieces close to each other and in parallel to a propagation direction of the SAW resonator, wherein the IDT electrode positioned in the center is totally grounded on at least the two sides of the IDT electrode not adjacent to the reflectors, and wherein other IDT electrodes of said SAW filter disposed outside said center are electrically independent.
A surface acoustic wave (SAW) filter, comprising two SAW resonators, each of said two SAW resonators comprising an inter-digital transducer (IDT) electrode having at least four sides and reflectors adjacent to two sides of the IDT electrode, the two SAW resonators being disposed on a surface of a piezoelectric substrate, wherein said SAW resonators are formed in parallel to a propagation direction of said SAW resonators, the IDT electrodes are grounded on at least the two sides of the IDT electrodes not adjacent to the reflectors, and between said SAW resonators, a periodic-structured electrode row is present comprising stripline electrodes having about the same length as an IDT electrode overlap width of said SAW resonators, wherein said stripline electrodes are parallel-disposed at the same electrode period as in said SAW resonators, and said SAW resonators and said periodic-structured electrode row form an acoustic coupling by being disposed close to each other.
A surface acoustic wave (SAW) filter comprising two SAW resonators disposed on a surface of a piezoelectric substrate, a first SAW resonator comprising at least three pieces, an inter-digital transducer (IDT) electrode having at least four sides and two reflectors wherein the IDT electrode is disposed between the two reflectors, wherein said IDT electrode is grounded on at least two sides of the IDT electrode not adjacent to the reflectors, wherein the two SAW resonators form an acoustic coupling by being disposed close to each other, wherein electrodes of the first SAW resonator are arranged to be opposite in phase, and electrodes of a second SAW resonator are arranged to be equal in phase, and wherein said first SAW resonator and said second SAW resonator are parallel-connected.
A surface acoustic wave (SAW) filter comprising a SAW resonator disposed on a surface of a piezoelectric substrate, the SAW resonator comprising at least five pieces, an inter-digital transducer (IDT) electrode having at least four sides and reflectors disposed adjacent to two sides of the IDT electrode, wherein said IDT electrode is grounded on at least the two sides of the IDT electrode not adjacent to the reflectors, wherein said SAW resonator form an acoustic coupling by disposing the at least five pieces close to each other, wherein electrodes of the SAW resonator comprising a first and a second SAW resonator filter are arranged to be opposite in phase, and electrodes of the SAW resonator comprising a third and a fourth SAW resonator filter are arranged to be equal in phase, wherein said first SAW resonator filter and said third SAW resonator filter are parallel-connected and said second and said fourth SAW resonator filters are parallel-connected, and wherein said first and said third SAW resonator filters and said second and said fourth SAW resonator filters are concatenately connected through electrode patterns formed between said filters on the surface of said piezoelectric substrate.
A surface acoustic wave (SAW) filter comprising a SAW resonator disposed on a surface of a piezoelectric substrate, the SAW resonator comprising an inter-digital transducer (IDT) electrode having at least four sides and reflectors adjacent to two sides of the IDT electrode, wherein the IDT electrode is grounded on at least the two sides of the IDT electrode not adjacent to the reflectors, wherein the SAW resonator forms acoustic coupling by disposing the IDT electrode and reflectors close to each other, wherein electrode patterns for bus bars are divided at a central part of an electrode adjacent to the SAW resonator, and wherein other SAW resonators disposed on the piezoelectric substrate have electrically independent bus bars.
A surface acoustic wave (SAW) filter comprising a SAW resonator disposed on a surface of a piezoelectric substrate, the SAW resonator comprising at least five pieces, an inter-digital transducer (IDT) electrode having at least four sides disposed in the center of the SAW filter and reflectors disposed adjacent to two sides of the IDT electrode, wherein said IDT electrode is grounded on at least the two sides of the IDT electrode not adjacent to the reflectors, wherein the SAW resonator forms an acoustic coupling by disposing the at least five pieces close to each other, wherein electrode patterns for bus bars are divided at the central part of the SAW resonator, and the at least five pieces of said SAW resonator are present such that electrodes of the SAW resonator comprising a first and a second SAW resonator filter are arranged to be opposite in phase, and electrodes of the SAW resonators comprising a third and a fourth SAW resonator filter are arranged to be equal in phase, and said first SAW resonator filter and said third SAW resonator filter are parallel-connected and said second and said fourth SAW resonator filters are parallel-connected, and wherein said first and said third SAW resonator filters are concatenately connected to said second and said fourth SAW resonator filters through electrode patterns formed between the filters on the surface of said piezoelectric substrate.
A surface acoustic wave (SAW) filter comprising a reactive element formed by using a part of electrode patterns of a SAW filter, wherein the reactive element is disposed with an inter-digital transducer (IDT) electrode having at least four sides and reflector electrodes, said reactive element is formed adjacent to said reflector electrodes, and wherein said IDT electrode is grounded on at least two sides of the IDT electrode not adjacent to the reflector electrodes.
A surface acoustic wave (SAW) filter comprising a SAW resonator disposed with an inter-digital transducer (IDT) electrode having at least four sides and reflectors disposed adjacent to two sides of the IDT electrode, wherein said IDT electrode is grounded on at least the two sides of the IDT electrode not adjacent to the reflectors, wherein a plurality of SAW resonators form an acoustic coupling by being disposed close to each other on a surface of a same piezoelectric substrate, wherein said plurality of SAW resonators are concatenately connected, and wherein an input-output matching circuit is formed by using a reactive element formed by an electrode pattern disposed on the surface of said piezoelectric substrate.
A surface acoustic wave (SAW) filter comprising a SAW resonator disposed on a surface of a piezoelectric substrate, the SAW resonator comprising an inter-digital transducer (IDT) electrode in the center of the SAW filter, said IDT electrode having at least four sides, and reflectors adjacent to two sides of the IDT electrode, wherein said IDT electrode is grounded on at least the two sides of the IDT electrode not adjacent to the reflectors, wherein a plurality of SAW resonators form an acoustic coupling by being disposed closely to each other on the surface of the piezoelectric substrate, wherein said plurality of SAW resonators are concatenately connected, and wherein connecting points of said plurality of SAW resonators are grounded via a reactive element formed by an electrode pattern disposed on the surface of the piezoelectric substrate.
Dependencies are inferred from the claim text.