Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2007-01-26
2009-02-10
Budd, Mark (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S365000, C310S320000
Reexamination Certificate
active
07489063
ABSTRACT:
An object of the present invention is to provide an inexpensive thin film piezoelectric bulk acoustic wave resonator that allows fine-tuning of a resonant frequency. Another object is to provide an inexpensive filter with dramatically improved frequency characteristics, using thin film piezoelectric bulk acoustic wave resonators that can be formed on one substrate. A thin film piezoelectric bulk acoustic wave resonator of the present invention has a laminated structure including a piezoelectric thin film, and a first metal electrode film and a second metal electrode film between which part of the piezoelectric thin film is sandwiched; the first metal electrode film has a plurality of holes formed on an electrode plane opposite to the second metal electrode film and having a depth equivalent to at least the thickness of the first metal electrode film; and if a combined thickness of top and bottom electrode layers and the piezoelectric thin film is ht, the covering ratio σ of the electrode plane of the first metal electrode film satisfies a condition 0<σ<1 for every 1.28 ht pitch.
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Asai Kengo
Isobe Atsushi
Matsumoto Hisanori
Shibagaki Nobuhiko
Budd Mark
Hitachi Media Electronics Co. Ltd.
Miles & Stockbridge P.C.
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