THIN-FILM PIEZOELECTRIC RESONATOR AND FILTER CIRCUIT

a lower electrode (11) provided on the principal surface of the substrate (10) so as to cover the cavity (14); a piezoelectric film (12) provided on the lower electrode (11) so as to be located above the cavity (14); and an upper electrode (13). The upper electrode (13) has a main portion (13a) whic...

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Bibliographic Details
Main Authors YASUMOTO TAKAAKI, SANO KENYA, YANASE NAOKO, OHARA RYOICHI, ITAYA KAZUHIKO
Format Patent
LanguageEnglish
Published 29.08.2007
Subjects
BASIC ELECTRONIC CIRCUITRY
ELECTRICITY
IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS
RESONATORS
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Summary:a lower electrode (11) provided on the principal surface of the substrate (10) so as to cover the cavity (14); a piezoelectric film (12) provided on the lower electrode (11) so as to be located above the cavity (14); and an upper electrode (13). The upper electrode (13) has a main portion (13a) which overlaps a part of the cavity (14), a protruding portion (13b) connected on one side to the main portion (13), a connecting portion (13c) provided at the opposite side of the main portion (13), and an extension portion (13d) connected to the connecting portion (13c). The length of the protruding portion (13b) is substantially the same as the length of the connecting portion (13c), so that the overlap area of the upper (13) and lower (11) electrodes outside the cavity region is constant with respect to a shift of the cavity (14) location. As a result, the total sum of the parasitic capacitances in the upper (13) and lower (11) electrodes facing each other outside the cavity (14) does not vary with a shift of the cavity (14) location.
Bibliography:Application Number: KR20077014429