US 12,712,525 B2Granted

Acoustic wave filter device

AssigneeMurata Manufacturing Co., Ltd.

InventorAkira Noguchi

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Abstract

In a plan view in a thickness direction of a piezoelectric substrate, each of acoustic wave resonators includes a central region, a first region having a lower acoustic wave velocity than that of the central region, and a second region having a lower acoustic wave velocity than that of the central region. A first acoustic wave resonator includes a third region having a gap of about 0.3λ or longer in a predetermined direction outside of the first region and having a higher acoustic velocity of the acoustic wave than that of the central region, and a fourth region having a gap of about 0.3λ or longer in the predetermined direction outside of the second region and having a higher acoustic velocity of the acoustic wave than that of the central region. A second acoustic wave resonator does not include the third and fourth regions.

Claims19

Dependent claims

An acoustic wave filter device comprising:

a plurality of acoustic wave resonators each including:
a piezoelectric substrate;
and
an IDT electrode on the piezoelectric substrate;
the IDT electrode includes:
a first busbar;
a second busbar facing the first busbar in a predetermined direction;
a plurality of first electrode fingers extending from the first busbar toward the second busbar in the predetermined direction;
and
a plurality of second electrode fingers extending from the second busbar toward the first busbar in the predetermined direction;
a region between an envelope of tip edges of the plurality of first electrode fingers and an envelope of tip edges of the plurality of second electrode fingers is defined as an intersecting region;
a wavelength of an acoustic wave determined by an electrode finger pitch of the IDT electrode is defined as λ;
in a plan view in a thickness direction of the piezoelectric substrate, each of the plurality of acoustic wave resonators includes:
a central region including a central portion of the intersecting region of the IDT electrode in the predetermined direction;
a first region including tip end portions of the plurality of first electrode fingers and having a lower acoustic velocity of an acoustic wave than that of the central region;
and
a second region including tip end portions of the plurality of second electrode fingers and having a lower acoustic velocity of an acoustic wave than that of the central region;
the plurality of acoustic wave resonators include:
a first acoustic wave resonator;
and
a second acoustic wave resonator;
the piezoelectric substrate of the first acoustic wave resonator and the piezoelectric substrate of the second acoustic wave resonator are the same;
the first acoustic wave resonator further includes:
a third region having a gap having a length of about 0.3λ or longer and less than 2.0λ in the predetermined direction outside of the first region in the predetermined direction and having a higher acoustic velocity of an acoustic wave than that of the central region;
and
a fourth region having a gap having a length of about 0.3λ or longer and less than 2.0λ in the predetermined direction outside of the second region in the predetermined direction and having a higher acoustic velocity of an acoustic wave than that of the central region;
and
the second acoustic wave resonator does not include the third region and the fourth region.

25 more elements

An acoustic wave filter device comprising:

a plurality of acoustic wave resonators each including:
a piezoelectric substrate;
and
an IDT electrode on the piezoelectric substrate;
the IDT electrode includes:
a first busbar;
a second busbar facing the first busbar in a predetermined direction;
a plurality of first electrode fingers extending from the first busbar toward the second busbar in the predetermined direction;
and
a plurality of second electrode fingers extending from the second busbar toward the first busbar in the predetermined direction;
a region between an envelope of tip edges of the plurality of first electrode fingers and an envelope of tip edges of the plurality of second electrode fingers is defined as an intersecting region;
a wavelength of an acoustic wave determined by an electrode finger pitch of the IDT electrode is defined as λ;
in a plan view in a thickness direction of the piezoelectric substrate, each of the plurality of acoustic wave resonators includes:
a central region including a central portion of the intersecting region of the IDT electrode in the predetermined direction;
a first region including tip end portions of the plurality of first electrode fingers and including a first mass addition film overlapping at least a portion of the tip end portion of at least one first electrode finger in the plurality of first electrode fingers;
and
a second region including tip end portions of the plurality of second electrode fingers and including a second mass addition film overlapping at least a portion of the tip end portion of at least one second electrode finger in the plurality of second electrode fingers;
the tip end portion of the plurality of first electrode fingers is a portion including the tip edge of the first electrode finger;
the tip end portion of the plurality of second electrode fingers is a portion including the tip edge of the second electrode finger;
the plurality of acoustic wave resonators include:
a first acoustic wave resonator;
and
a second acoustic wave resonator;
the piezoelectric substrate of the first acoustic wave resonator and the piezoelectric substrate of the second acoustic wave resonator are the same;
the first acoustic wave resonator further includes:
a third region having a gap having a length of about 0.3λ or longer and less than 2.0λ in the predetermined direction outside of the first region in the predetermined direction;
and
a fourth region having a gap having a length of about 0.3λ or longer and less than 2.0λ in the predetermined direction outside of the second region in the predetermined direction;
and
the second acoustic wave resonator does not include the third region and the fourth region.

27 more elements

An acoustic wave filter device comprising:

a plurality of acoustic wave resonators each including:
a piezoelectric substrate;
and
an IDT electrode on the piezoelectric substrate;
the IDT electrode includes:
a first busbar;
a second busbar facing the first busbar in a predetermined direction;
a plurality of first electrode fingers extending from the first busbar toward the second busbar in the predetermined direction;
and
a plurality of second electrode fingers extending from the second busbar toward the first busbar in the predetermined direction;
a region between an envelope of tip edges of the plurality of first electrode fingers and an envelope of tip edges of the plurality of second electrode fingers is defined as an intersecting region;
a wavelength of an acoustic wave determined by an electrode finger pitch of the IDT electrode is defined as λ;
in a plan view in a thickness direction of the piezoelectric substrate, each of the plurality of acoustic wave resonators includes:
a central region including a central portion of the intersecting region of the IDT electrode in the predetermined direction;
a first region including tip end portions of the plurality of first electrode fingers, the tip end portion of at least one first electrode finger in the plurality of first electrode fingers including a first wide portion;
and
a second region including tip end portions of the plurality of second electrode fingers, the tip end portion of at least one second electrode finger in the plurality of second electrode fingers including a second wide portion;
a width of the first wide portion is wider than a width of the central portion of the at least one first electrode finger;
a width of the second wide portion is wider than a width of the central portion of the at least one second electrode finger;
the plurality of acoustic wave resonators include:
a first acoustic wave resonator;
and
a second acoustic wave resonator;
the piezoelectric substrate of the first acoustic wave resonator and the piezoelectric substrate of the second acoustic wave resonator are the same;
the first acoustic wave resonator further includes:
a third region having a gap having a length of about 0.3λ or longer and less than 2.0λ in the predetermined direction outside of the first region in the predetermined direction;
and
a fourth region having a gap having a length of about 0.3λ or longer and less than 2.0λ in the predetermined direction outside of the second region in the predetermined direction;
and
the second acoustic wave resonator does not include the third region and the fourth region.

27 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/604,619Filed 14 Mar 2024
Priority: JP 2023-06507012 Apr 2023
Published: US 2024/0348233 A117 Oct 2024
Granted: 18 Aug 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

H03H 9/6483
Coupled resonator filters: ladder SAW filters
H03H 9/02015
Of bulk acoustic wave devices: characteristics of piezoelectric layers, e.g. cutting angles
H03H 9/02574
Characteristics of substrate, e.g. cutting angles: of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical…
H03H 9/02992
Of surface acoustic wave devices: details of bus bars, contact pads or other electrical connections for finger electrodes