| US 7,394,336 B2 | ||
| Elastic boundary wave apparatus | ||
| Hajime Kando, Ritto (Japan) | ||
| Assigned to Murata Manufacturing Co. Ltd., Kyoto (US) | ||
| Filed on Oct. 26, 2007, as Appl. No. 11/924,873. | ||
| Application 11/924873 is a continuation of application No. PCT/JP2006/308597, filed on Apr. 25, 2006. | ||
| Claims priority of application No. 2005-142839 (JP), filed on May 16, 2005. | ||
| Prior Publication US 2008/0042781 A1, Feb. 21, 2008 | ||
| Int. Cl. H03H 9/145 (2006.01); H03H 9/25 (2006.01); H03H 9/64 (2006.01) | ||
| U.S. Cl. 333—193 [333/195; 310/313 B] | 7 Claims |
| 1. An elastic boundary wave apparatus comprising:
a first medium;
a second medium stacked on the first medium; and
a plurality of electrodes arranged in a boundary between the first and second media; wherein
a filter and/or a resonator, and an electrostatic capacitor that is electrically connected to the filter and/or the resonator
are defined by the plurality of electrodes;
the filter and/or the resonator each include an IDT electrode;
the electrostatic capacitor includes a comb-shaped capacitor electrode; and
when a period of the electrode fingers of the IDT is denoted as λm, a sound velocity of an elastic boundary wave in the IDT
is denoted as Vm, a period of electrode fingers of the comb-shaped capacitor electrode is denoted as λc, and a sound velocity
of a transverse wave having a lower sound velocity among the lower sound velocities of transverse waves through the first
and second media in the normal direction of the electrode fingers of the comb-shaped capacitor electrode is denoted as Vc,
a relationship Vm/λm<Vc/λc is satisfied.
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