An acoustic wave device includes a support substrate having a thickness in a first direction, a piezoelectric layer on the support substrate, and an interdigital transducer electrode on the piezoelectric layer and including first and second electrode fingers extending in a second direction crossing the first direction. The second electrode fingers face the first electrode fingers in a third direction orthogonal or substantially orthogonal to the second direction. The support substrate and the piezoelectric layer include a hollow therebetween at a position at least partially overlapping the interdigital transducer electrode in the first direction. At least one through hole penetrates the piezoelectric layer at a position not overlapping the interdigital transducer electrode in the first direction, and the through hole communicates with the hollow. A reinforcing support extends inside the hollow in a region overlapping the hollow and not overlapping the first and second electrode fingers.

An acoustic wave device includes a support substrate having a thickness in a first direction, a piezoelectric layer on the support substrate, an interdigital transducer electrode on the piezoelectric layer and including first and second electrode fingers, the first electrode fingers extending in a second direction crossing the first direction, the second electrode fingers extending in the second direction and facing the first electrode fingers in a third direction orthogonal or substantially orthogonal to the second direction, and a reinforcing film on the piezoelectric layer. The support substrate and the piezoelectric layer include a hollow therebetween at a position overlapping the interdigital transducer electrode in the first direction. At least one through hole penetrates the piezoelectric layer at a position not overlapping the interdigital transducer electrode in the first direction, and the through hole communicates with the hollow. The reinforcing film overlaps the hollow in the first direction.

A SAW transducer and a SAW resonator are proposed composed of consecutively arranged unit cells of length L. Slight geometry or material variations such as variations of the metallization ration or the unit cell length L affecting the pitch) between these unit cells result in improved spurious mode suppression while the main mode performance is unaffected.

The present disclosure relates to acoustic wave devices, and particularly to high quality factor (Q) transducers for surface acoustic wave (SAW) devices. An exemplary SAW device includes an interdigital transducer (IDT) between two reflective gratings to form a resonator. The resonator operates through shear horizontal mode acoustic waves, and therefore suppression of transverse modes (parallel to electrode fingers of the IDT) is desired. A piston mode can be formed in the resonator to suppress transverse modes, which may also increase energy leakage and result in a lower Q. A higher Q is achieved by adding a fast region at an end of one or more of the electrode fingers of the IDT.

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.

In an acoustic wave device, a piezoelectric layer is provided directly or indirectly on a support substrate, an IDT electrode is provided on the piezoelectric layer, an overlap region includes a middle region and first and second edge regions, and first and second conductive layers are provided on a second main surface of the piezoelectric layer to overlap at least some portions of the first and second edge regions in plan view and at least some portions of first and second busbars in plan view.

An acoustic wave resonator includes a piezoelectric body and electrode fingers. The electrode fingers are positioned on the piezoelectric body and arrayed in a propagation direction of acoustic waves. The electrode fingers include a first and second electrode finger groups. Electrode fingers are formed between adjacent two of the electrode fingers of the other electrode group. A duty ratio of the electrode fingers of the first and second electrode finger groups is gradually changed along one of opposite directions specifying the propagation direction by first and second change amounts, respectively which are different, and in the opposite direction. In a region in which the electrode fingers are positioned, a pitch between the electrode fingers is changed to cancel an effect of a difference in the duty ratio of the electrode fingers on a difference in resonance frequency.

A resonator includes: interdigital transducer (IDT) including first electrode including first base on piezoelectric substrate and extended in reference direction, and first protrusions connected to the first base and extended in direction intersecting with the reference direction, and second electrode including second base on the piezoelectric substrate and extended in the reference direction, and second protrusions connected to the second base and extended in direction intersecting with the reference direction, each of the second protrusions extended to have one of the first protrusions inserted between the second protrusion and another second protrusion adjacent to the second protrusion, wherein a width of each of first specific protrusions included between one end of the IDT and first position at first distance from the one end, among the first protrusions and the second protrusions, decreases from first specific protrusion closest to the first position toward first specific protrusion closest to the one end.

An acoustic wave device with a bent section is disclosed. The acoustic wave device includes a piezoelectric layer and an interdigital transducer electrode on the piezoelectric layer. The bent section is arranged to create a curvature in a waveguide of the acoustic wave device to suppress a transverse spurious mode of the acoustic wave device.

A longitudinally coupled resonator acoustic wave filter includes a piezoelectric substrate, IDT electrodes on the piezoelectric substrate along an acoustic wave propagation direction, and a pair of reflectors on the piezoelectric substrate on both sides of the IDT electrodes in the acoustic wave propagation direction. Each of the reflectors includes first and second reflector busbars, and first reflective electrode fingers connected to at least one of the first reflector busbar and the second reflector busbar. The reflector includes a first portion in which lengths of the first reflective electrode fingers change in the acoustic wave propagation direction.