US 2011/0316647 A1Published application

Elastic wave branching filter

AssigneeMurata Manufacturing Co., Ltd.

InventorsMinefumi OUCHI, Tomohisa KOMURA

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Abstract

A reception filter includes a first and second longitudinally coupled resonator-type surface acoustic wave filter portions and a surface acoustic wave resonator. The first and second longitudinally coupled resonator-type surface acoustic wave filter portions each include at least three IDT electrodes. The surface acoustic wave resonator includes one IDT electrode connected to at least one of the at least three IDT electrodes. The reception filter is arranged such that a ratio of a capacitance of the surface acoustic wave resonator to a capacitance of each of the at least one of the at least three IDT electrodes included in the longitudinally coupled resonator-type surface acoustic wave filter portion, the at least one of the at least three IDT electrodes being electrically connected to the one IDT electrode of the surface acoustic wave resonator, is in the range of about 1.9 to about 2.5.

Claims4

Dependent claims

An elastic wave branching filter comprising:

an antenna terminal;
a reception signal terminal;
a transmission signal terminal;
a reception filter connected between the antenna terminal and the reception signal terminal;
and
a transmission filter connected between the antenna terminal and the transmission signal terminal;
wherein
the reception filter includes:
a longitudinally coupled resonator-type elastic wave filter portion connected between the antenna terminal and the reception signal terminal and including at least three IDT electrodes arranged in an elastic wave propagation direction;
and
an elastic wave resonator connected between the longitudinally coupled resonator-type elastic wave filter portion and the antenna terminal and including one IDT electrode connected to at least one of the at least three IDT electrodes of the longitudinally coupled resonator-type elastic wave filter portion;
and
the reception filter is arranged such that a ratio of C1 to C2 is in a range of about 1.9 to about 2.5, where C1 is a capacitance of the elastic wave resonator and C2 is a capacitance of the at least one of the at least three IDT electrodes of the longitudinally coupled resonator-type elastic wave filter portion.

10 more elements

Dependencies are inferred from the claim text.