An acoustic wave filter device includes at least one series arm resonator and a parallel arm resonator. The series arm resonators and the parallel arm resonator are defined by acoustic wave resonators, an interdigital transducer electrode of the series arm resonators is an apodized interdigital transducer electrode subjected to apodization weighting, in the interdigital transducer electrode of the parallel arm resonator, an intersecting portion includes a central region and low acoustic velocity regions provided at both outer side portions of the central portion, an acoustic velocity of an acoustic wave in the low acoustic velocity region is lower than an acoustic velocity of an acoustic wave in the central region, and a high acoustic velocity region where an acoustic velocity of an acoustic wave is higher than that of the low acoustic velocity region is provided at an outer side portion of each of the low acoustic velocity regions.

An acoustic wave device is disclosed. The acoustic waved device can be a shear horizontal mode surface acoustic wave device. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode over the piezoelectric layer, and a temperature compensation layer over the interdigital transducer electrode. The piezoelectric layer can be a lithium niobate layer with a cut angle in a range of −20° YX to 25° YX. The interdigital transducer electrode includes a first layer having a first thickness and a second layer having a second thickness. The first layer affects acoustic properties of the acoustic wave device and the second layer affects electrical properties of the acoustic wave device. The first layer is positioned between the piezoelectric layer and the second layer. The first thickness is configured such that a frequency response of the acoustic wave device includes a Rayleigh mode response at a frequency higher than a shear horizontal mode response resonance. The first thickness can be greater than the second thickness.

An acoustic wave device is disclosed. The acoustic waved device can be a shear horizontal mode surface acoustic wave device. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode over the piezoelectric layer, and a temperature compensation layer over the interdigital transducer electrode. The piezoelectric layer can be a lithium niobate layer with a cut angle in a range of −20° YX to 25° YX. The interdigital transducer electrode includes a first layer having a first thickness and a second layer having a second thickness. The first layer affects acoustic properties of the acoustic wave device and the second layer affects electrical properties of the acoustic wave device. The first layer is positioned between the piezoelectric layer and the second layer. The first thickness is configured such that a frequency response of the acoustic wave device includes a Rayleigh mode response at a frequency higher than a shear horizontal mode response resonance. The first thickness can be greater than the second thickness.

An acoustic wave resonator includes two comb-shaped electrodes provided on a piezoelectric substrate, each of the comb-shaped electrodes including electrode fingers and a bus bar coupled to the electrode fingers, an acoustic velocity of an acoustic wave propagating through a gap region, which is located between tips of electrode fingers of one of the comb-shaped electrodes and a bus bar of the other of the comb-shaped electrodes, being equal to or greater than 0.98 times and equal to or less than 1.02 times an acoustic velocity of an acoustic wave propagating through an edge region located in an edge in an extension direction of the electrode fingers in an overlap region, and an additional film that is provided over the piezoelectric substrate from the edge region to the gap region and is not provided in a center region located further in than the edge region in the overlap region.

An acoustic wave resonator includes two comb-shaped electrodes provided on a piezoelectric substrate, each of the comb-shaped electrodes including electrode fingers and a bus bar coupled to the electrode fingers, an acoustic velocity of an acoustic wave propagating through a gap region, which is located between tips of electrode fingers of one of the comb-shaped electrodes and a bus bar of the other of the comb-shaped electrodes, being equal to or greater than 0.98 times and equal to or less than 1.02 times an acoustic velocity of an acoustic wave propagating through an edge region located in an edge in an extension direction of the electrode fingers in an overlap region, and an additional film that is provided over the piezoelectric substrate from the edge region to the gap region and is not provided in a center region located further in than the edge region in the overlap region.

An elastic wave device includes a piezoelectric film laminated on a first main surface of a support substrate including a recessed portion open to a first main surface. A cavity portion including the recessed portion is defined by the support substrate and the piezoelectric film. An electrode is on the piezoelectric film. The electrode includes first and second bus bars, a first electrode finger connected to the first bus bar, and a second electrode finger connected to the second bus bar. The first and second bus bars include corner portions inside the cavity portion when viewed in plan view. A curved portion as a pressure relaxation portion to relax pressure on the piezoelectric film at at least one of the corner portions of the first and second bus bars is provided between the corner portion and an outer edge of the cavity portion.

Aspects of this disclosure relate to acoustic wave devices on stacked die. A first die can include first acoustic wave device configured to generate a boundary acoustic wave. A second die can include a second acoustic wave device configured to generate a second boundary acoustic wave, in which the second die is stacked with the first die. The first acoustic wave resonator can include a piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer, and high acoustic velocity layers on opposing sides of the piezoelectric layer. The high acoustic velocity layers can each have an acoustic velocity that is greater than a velocity of the boundary acoustic wave.

Aspects of this disclosure relate to acoustic wave devices on stacked die. A first die can include first acoustic wave device configured to generate a boundary acoustic wave. A second die can include a second acoustic wave device configured to generate a second boundary acoustic wave, in which the second die is stacked with the first die. The first acoustic wave resonator can include a piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer, and high acoustic velocity layers on opposing sides of the piezoelectric layer. The high acoustic velocity layers can each have an acoustic velocity that is greater than a velocity of the boundary acoustic wave.

A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode. The first interdigital transducer electrode may be single-ended with a first input bus bar that receives an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The front-end module may include a low noise amplifier (LNA) that outputs a differential signal via a differential output and has a differential input connected to the acoustic wave filter. The LNA may include a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.

A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode. The first interdigital transducer electrode may be single-ended with a first input bus bar that receives an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The front-end module may include a low noise amplifier (LNA) that outputs a differential signal via a differential output and has a differential input connected to the acoustic wave filter. The LNA may include a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.