US 11,962,287 B2Granted

Acoustic wave filter

AssigneeMurata Manufacturing Co., Ltd.

InventorYuta Takeuchi

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Abstract

An acoustic wave filter includes series arm resonators and parallel arm resonators each including an acoustic wave resonator including an IDT electrode including a pair of comb-shaped electrodes each including electrode fingers and a busbar electrode. An electrode finger connected to neither of the busbar electrodes of the pair of comb-shaped electrodes is a floating withdrawal electrode, and of all the electrode fingers of the pair of comb-shaped electrodes, the electrode finger that is connected to a same busbar electrode to which the electrode fingers on both sides thereof are connected is a polarity-reversing withdrawal electrode, and, of the series arm resonators, the series arm resonator having a lowest anti-resonant frequency includes an IDT electrode including the floating withdrawal electrodes, and the series arm resonator includes an IDT electrode including the polarity-reversing withdrawal electrodes.

Claims20

Dependent claims

An acoustic wave filter comprising:

a first input/output terminal and a second input/output terminal;
a plurality of series arm resonators along a path connecting the first input/output terminal and the second input/output terminal;
and
one or more parallel arm resonators each between a node in the path and ground;
wherein
each of the plurality of series arm resonators and the one or more parallel arm resonators includes an acoustic wave resonator that includes an interdigital transducer (IDT) electrode on a substrate having piezoelectricity;
the IDT electrode includes a pair of comb-shaped electrodes each including a plurality of electrode fingers and a busbar electrode, the plurality of electrode fingers being in parallel or substantially in parallel to one another and extending in a direction that crosses an acoustic wave propagation direction, the busbar electrode connecting one-end portions of the electrode fingers of the plurality of electrode fingers;
of the plurality of electrode fingers, an electrode finger not connected to either one of the busbar electrodes of the pair of comb-shaped electrodes is a floating withdrawal electrode;
and
of the plurality of electrode fingers, an electrode finger connected to a same busbar electrode to which electrode fingers on both sides thereof are connected is a polarity-reversing withdrawal electrode;
of the plurality of series arm resonators, a first series arm resonator having a lowest anti-resonant frequency includes an IDT electrode including the floating withdrawal electrode;
and
of the plurality of series arm resonators, at least one series arm resonator other than the first series arm resonator includes an IDT electrode including the polarity-reversing withdrawal electrode.

10 more elements

An acoustic wave filter comprising:

a first input/output terminal and a second input/output terminal;
one or more series arm resonators along a path connecting the first input/output terminal and the second input/output terminal;
and
a plurality of parallel arm resonators each between a node in the path and ground;
wherein
each of the one or more series arm resonators and the plurality of parallel arm resonators includes an acoustic wave resonator that includes an IDT electrode on a substrate having piezoelectricity;
the IDT electrode includes a pair of comb-shaped electrodes each including a plurality of electrode fingers and a busbar electrode, the plurality of electrode fingers being in parallel or substantially in parallel to one another and extending in a direction that crosses an acoustic wave propagation direction, the busbar electrode connecting one-end portions of the electrode fingers of the plurality of electrode fingers;
of the plurality of electrode fingers, an electrode finger not connected to either one of the busbar electrodes of the pair of comb-shaped electrodes is a floating withdrawal electrode;
of all of the electrode fingers of the pair of comb-shaped electrodes, an electrode finger connected to a same busbar electrode to which electrode fingers on both sides thereof are connected is defined as a polarity-reversing withdrawal electrode;
of the plurality of parallel arm resonators, a first parallel arm resonator having a highest resonant frequency includes an IDT electrode including the polarity-reversing withdrawal electrode;
and
of the plurality of parallel arm resonators, at least one of the parallel arm resonators other than the first parallel arm resonator includes an IDT electrode including the floating withdrawal electrode.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/582,591Filed 24 Jan 2022 · continuation
Priority: JP 2019-13688325 Jul 2019
Published: US 2022/0149818 A112 May 2022
Granted: 16 Apr 2024
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H03H 9/02574
Characteristics of substrate, e.g. cutting angles: of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical…
H03H 9/64
Filters: using surface acoustic waves
H03H 9/02992
Of surface acoustic wave devices: details of bus bars, contact pads or other electrical connections for finger electrodes
H03H 9/13
Driving means, e.g. electrodes, coils: for networks consisting of piezoelectric or electrostrictive materials