Acoustic wave device
AssigneeMurata Manufacturing Co., Ltd.
InventorKatsuya Daimon
Life of this patent
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Abstract
An acoustic wave device includes a high-acoustic-velocity film, a low-acoustic-velocity film, a piezoelectric layer including lithium tantalate, and an IDT electrode on the piezoelectric layer. The IDT electrode includes first and second busbars and first and second electrode fingers. An intersecting region is a portion where the first and second electrode fingers overlap in an acoustic wave propagation direction. The intersecting region includes a central region and first and second edge regions. The IDT electrode includes first and second gap regions outside the first and second edge regions. The first and second electrode fingers are wider in the first and second edge regions than in the central region. A duty ratio in the first and second edge regions is from about 0.62 to about 0.73.
Claims20
An acoustic wave device comprising:
- a high-acoustic-velocity material layer;
- a low-acoustic-velocity film on the high-acoustic-velocity material layer;
- a piezoelectric layer including lithium tantalate on the low-acoustic-velocity film;
- and
- an interdigital transducer (IDT) electrode on the piezoelectric layer;
- wherein
- an acoustic velocity of bulk waves propagating through the high-acoustic-velocity material layer is higher than an acoustic velocity of acoustic waves propagating through the piezoelectric layer;
- an acoustic velocity of bulk waves propagating through the low-acoustic-velocity film is lower than an acoustic velocity of bulk waves propagating through the piezoelectric layer;
- the IDT electrode includes a first busbar and a second busbar facing each other, a plurality of first electrode fingers each including one end connected to the first busbar, and a plurality of second electrode fingers each including one end connected to the second busbar and that are interdigitated with the plurality of first electrode fingers;
- when an acoustic wave propagation direction is a first direction and a direction perpendicular to the first direction is a second direction, a portion of the IDT electrode where the first electrode fingers and the second electrode fingers overlap in the first direction is an intersecting region;
- the intersecting region includes a central region centrally located in the second direction, a first edge region at a side of the central region closer to the first busbar, and a second edge region at a side of the central region closer to the second busbar;
- the IDT electrode includes a first gap region between the first edge region and the first busbar and a second gap region between the second edge region and the second busbar;
- the first electrode fingers and the second electrode fingers are wider in at least one region of the first edge region and the second edge region than in the central region;
- and
- a duty ratio in the first edge region and the second edge region is from 0.62 to 0.73.
Dependencies are inferred from the claim text.