A composite filter device includes an antenna common terminal, a first band pass filter having a first pass band, and a second band pass filter having a second pass band located at higher frequencies than the first pass band. The first band pass filter includes an elastic wave resonator. The elastic wave resonator includes a LiNbO.sub.3 substrate, an IDT electrode on the LiNbO.sub.3 substrate, and a dielectric film that covers the IDT electrode and includes a silicon oxide as a main component. When f1′ is the frequency of a Sezawa wave of the first band pass filter and f2 is the center frequency of the second pass band, f1′ is located at a different position from f2.

An acoustic wave device includes a piezoelectric substrate, interdigital transducer electrodes including a predetermined number of electrode fingers disposed on an upper surface of the substrate, and a dielectric material layer having a first portion and a second portion. The first portion is disposed on the upper surface of the substrate and between the interdigital transducer electrode fingers. The second portion is disposed above the interdigital transducer electrode fingers. The acoustic wave device further includes at least one thermally conductive bridge disposed within the dielectric material layer and contacting upper surfaces of at least two adjacent interdigital transducer electrode fingers to dissipate heat therefrom.

A filter device includes a first input/output terminal and a second input/output terminal, as well as a series-arm circuit disposed on a path that connects the first input/output terminal and the second input/output terminal, and a parallel-arm circuit connected to a node on the path and a ground. At least one of the series-arm circuit or the parallel-arm circuit includes a resonance circuit, and the resonance circuit includes a first acoustic wave resonator, and a first capacitor connected in parallel to the first acoustic wave resonator, and having a greater electrostatic capacitance per unit area than that for the first acoustic wave resonator.

An elastic wave device includes a piezoelectric material layer, an IDT electrode on the piezoelectric material layer, and a dielectric film covering the IDT electrode. The IDT electrode includes a first electrode layer and a second electrode layer laminated on the first electrode layer. Each of wavelength normalized film thicknesses of the first and second electrode layers is equal to or greater than about 1.25%, and is normalized using a wave length defined by the electrode finger pitch of the IDT electrode. The second electrode layer has a density lower than that of the first electrode layer. The side of the second electrode layer is inclined with respect to the thickness direction of the IDT electrode.

An electronic device comprises a first surface acoustic wave (SAW) resonator and a second SAW resonator, each including interleaved interdigital transducer (IDT) electrodes, the first and second SAW resonators being formed on a same piezoelectric substrate, the first SAW resonator having IDT electrodes with a different finger pitch than the IDT electrodes of the second SAW resonator; a dielectric material layer disposed on the IDT electrodes of the first and second SAW resonators; and a high velocity layer disposed within the dielectric material layer disposed on the IDT electrodes of the first SAW resonator, the second SAW resonator lacking a high velocity layer disposed within the dielectric material layer disposed on the IDT electrodes.

An acoustic wave device includes a piezoelectric body including first and second main surfaces facing each other, an IDT electrode provided on the first main surface of the piezoelectric body and including electrode fingers, a high acoustic velocity member on the second main surface side of the piezoelectric body, in which an acoustic velocity of a propagating bulk wave is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric body, and a first dielectric film provided on an upper surface of the electrode fingers, in which a portion where a dielectric is not present is provided between the electrode fingers of the IDT electrode.

An acoustic wave device includes a piezoelectric substrate including a piezoelectric layer made of lithium tantalate, an IDT electrode on the piezoelectric substrate, and a pair of reflectors on both sides of the IDT electrode on the piezoelectric substrate in an acoustic wave propagation direction. SH waves are used as a principal mode. The IDT electrode includes electrode fingers and the pair of reflectors each including electrode fingers. When a length along a direction orthogonal to a direction in which the electrode fingers extend is a width, each of the reflectors includes first and second electrode fingers having different widths. Four consecutive electrode fingers, which are any four of the electrode fingers of each of the reflectors, include both of the first and second electrode fingers and distances between centers of the four consecutive electrode fingers are equal or substantially equal.

Aspects of this disclosure relate to an acoustic wave device that includes a multi-layer interdigital transducer electrode. The acoustic wave device includes a piezoelectric layer and an interdigital transducer electrode on the piezoelectric layer. The interdigital transducer electrode includes a first interdigital transducer electrode layer positioned between a second interdigital transducer electrode layer and the piezoelectric layer. The second interdigital transducer electrode layer can include aluminum and having a thickness of at least 200 nanometers. The acoustic wave device can include a temperature compensation layer arranged such that the interdigital transducer electrode is positioned between the piezoelectric layer and at least a portion of the temperature compensation layer. Related filters, modules, wireless communication devices, and methods are disclosed.

An acoustic wave filter includes a piezoelectric substrate, first and second input-output terminals, and a longitudinally coupled resonator unit in a path connecting the first and second input-output terminals to each other, and the resonator unit includes five or more interdigital transducer electrodes aligned in an acoustic wave propagation direction, the IDT electrodes include a center IDT electrode at the center in the propagation direction and first and second IDT electrodes at symmetric or substantially symmetric positions in the propagation direction with respect to the center IDT electrode, each of the first and second IDT electrodes includes a main pitch portion and a pair of narrow-pitch portions provided between the main pitch portion and both ends of the IDT electrode in the propagation direction, and the first and second IDT electrodes differ from each other in the number of electrode fingers of the main pitch portion.

An elastic wave device includes a piezoelectric substrate, and elastic wave elements on the piezoelectric substrate and including IDT electrodes, respectively. The IDT electrode of a first of the elastic wave elements includes first and second busbars, and the IDT electrode of a second of the elastic wave elements includes third and fourth busbars. The second busbar and the third busbar extend parallel or substantially parallel to each other, and are spaced by a gap in a direction perpendicular or substantially perpendicular to an elastic-wave propagating direction. Each of the second and third busbars includes first and second electrode layers at least a portion of which is laminated on the first electrode layer. The second electrode layer of the second busbar is cut in at least one location in a direction crossing the elastic-wave propagating direction.