| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized broadband filter apparatus with a low loss. SOLUTION: The filter apparatus includes: a first signal side resonator S1 provided with an input signal electrode 1 and an output signal electrode 2, a first piezoelectric film 3, an input electrode film 4 connected to the input signal electrode 1; and a common electrode film 5 shared with a second signal side resonator S2 and using the input electrode film 4 to sandwich the first piezoelectric film 3; the second signal side resonator S2 provided with a second piezoelectric film 6 formed by being laminated on the first piezoelectric film 3, an output electrode film 7 connected to the output signal electrode 2, and a common electrode film 5 using the output electrode film 7 to hold the second piezoelectric film 6, and acoustically coupled to the first signal side resonator; and a ground side resonator P deposited between the common electrode film 5 and a ground electrode 8, and having an anti-resonance frequency nearly equal to a prescribed resonance frequency and the resonance frequency of the first and second signal side resonators S1, S2. COPYRIGHT: (C)2005,JPO&NCIPI
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