To provide a filter in which insertion loss in the pass band of the filter is reduced and to provide a filter unit and method of manufacturing the device.
In a ladder-type band pass filter 1 having a plurality of piezoelectric thin film resonators, the width of a wiring part 11 connecting two series resonators 110 arranged in a serial arm is designed to be wider than that of the series resonator 110. Thus, the resistance of connection parts is reduced. Further, the resistance of the connection parts is reduced by shortening the connection parts 11, 12 and 13 with an arrangement where the resonators (110, 120 and 130) are brought closer as much as possible. Consequently, insertion loss in the pass band is reduced. The film thickness of the wiring part 11 may be made thicker than that of an electrode part by stacking or growth.
NISHIHARA TOKIHIRO
SAKASHITA TAKESHI
YOKOYAMA TAKESHI
MIYASHITA TSUTOMU
FUJITSU LTD
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