Invention Grant
US08416036B2 Branching filter 有权
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Branching filter
Abstract:
A branching filter includes a longitudinally-coupled-resonator-type elastic wave filter having a balanced-unbalanced transformation function and the branching filter has excellent balance characteristics and a small size. The branching filter includes a ladder elastic wave filter chip and a longitudinally-coupled-resonator-type elastic wave filter chip. An antenna back-surface electrode and an antenna electrode pad are connected to each other via a first wiring provided in a wiring substrate. The antenna electrode pad and a longitudinally-coupled-resonator-type elastic wave filter are connected to each other via a second wiring provided on a piezoelectric substrate. The second wiring extends in a first direction and a first functional electrode and a second functional electrode provided on the piezoelectric substrate are axisymmetrically arranged with respect to each other about a central axis that extends in the first direction of the second wiring.
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