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US 5,581,141 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 three surface acoustic wave (SAW) resonators, each of said SAW resonators comprising an inter-digital transducer (IDT) electrode and reflectors on both sides of the IDT electrode, the SAW resonators being disposed on a surface of a piezoelectric substrate, wherein said SAW resonators form an acoustic coupling by being disposed close to each other in parallel to a propagation direction of the SAW resonators, wherein IDT electrodes of an adjacent pair of SAW resonators are electrically independent from each other, and wherein an IDT electrode of a SAW resonator positioned between two other SAW resonators is totally grounded.
Dependencies are inferred from the claim text.