Aspects of this disclosure relate to a surface acoustic wave resonator that may include a piezoelectric substrate, interdigital transducer (IDT) electrodes disposed on an upper surface of the piezoelectric substrate, and a dielectric film covering the piezoelectric substrate and the IDT electrode for temperature compensation. The IDT electrodes may include bus bar electrode regions spaced apart from each other in a transverse direction perpendicular to a propagation direction of a surface acoustic wave to be excited, an overlapping region sandwiched between the bus bar regions, and gap regions defined between respective bus bar electrode regions and the overlapping region in the transverse direction. Each of the gap regions may include a dummy electrode in a dummy electrode region extending from the bus bar electrode region in the transverse direction. The dielectric film may include an open region exposing a respective bus bar electrode region and dummy electrode region.

A multi band filter package is disclosed. The multi band filter can include a first acoustic wave filter that is mounted on a carrier, a second acoustic wave filter mounted on the carrier, and a ground pad on the carrier. The first acoustic wave filter has a first filter component and a first shunt resonator. The second acoustic wave filter has a second filter component and a second shunt resonator. The first and second acoustic wave filters are arranged such that the first and second shunt resonators are positioned between the first and second filter component. The first and second shunt resonators are coupled to the ground pad by way of an electrically conductive path. A least a portion of the electrically conductive path is positioned between the first and second shunt resonators.

A surface acoustic wave resonator that has at least a first resonant frequency and a second resonant frequency is disclosed. The surface acoustic wave resonator can include an interdigital transducer electrode that is positioned over a piezoelectric layer. The interdigital transducer electrode includes fingers having a first pitch. The surface acoustic wave resonator can also include a first set of reflectors that is positioned over the piezoelectric layer. The first set of reflectors includes a first number of reflectors having a second pitch. The first pitch is greater than the second pitch. The surface acoustic wave resonator can also include a second set of reflectors that is positioned over the piezoelectric layer. The second set of reflectors includes a second number of reflectors having a third pitch. The second number of reflectors is different from the first number of reflectors.

A surface acoustic wave resonator that has at least a first resonant frequency and a second resonant frequency is disclosed. The surface acoustic wave resonator can include an interdigital transducer electrode over a piezoelectric layer. The interdigital transducer electrode includes fingers having a first pitch. The surface acoustic wave resonator can also include a set of reflectors that is positioned over the piezoelectric layer. The set of reflectors includes a number of reflectors having a second pitch. The first pitch is greater than the second pitch. The number of reflectors is configured so as to compensate for degradation of a quality factor of the surface acoustic wave resonator due to having the first pitch greater than the second pitch.

Multi-mode surface acoustic wave filters are disclosed. A multi-mode surface acoustic wave filter can include a plurality of interdigital transducer electrodes that are longitudinally coupled to each other and slanted acoustic reflectors on opposing sides of the plurality of interdigital transducer electrodes. The acoustic reflectors include acoustic reflector fingers with slanted pitches.

Multi-mode surface acoustic wave filters are disclosed. A multi-mode surface acoustic wave filter can include a plurality of interdigital transducer electrodes that are longitudinally coupled to each other and stepped acoustic reflectors on opposing sides of the plurality of interdigital transducer electrodes. The acoustic reflectors include acoustic reflector fingers with stepped lengths.

An acoustic wave filter device includes first and second acoustic wave filters provided on a piezoelectric substrate, an insulating layer that is provided on the piezoelectric substrate and has a smaller dielectric constant than the piezoelectric substrate, a first wiring conductor electrically connected to an electrode of the first acoustic wave filter, a second wiring conductor electrically connected to an electrode of the second acoustic wave filter, the first wiring conductor and the second wiring conductor facing each other on the insulating layer in plan view, and a ground conductor located between the insulating layer and the piezoelectric substrate in a region A circumscribing the first wiring conductor and the second wiring conductor on the insulating layer in plan view.

A multiplexer (1) includes: a filter (13L) that is arranged between a common terminal (100) and an input/output terminal (130) and that has a first pass band; a filter (12H) that is arranged between the common terminal (100) and an input/output terminal (120), that is formed of at least one acoustic wave resonator, and that has a second pass band located at a higher frequency than the first pass band; and a capacitor (C2) that is serially arranged on a connection path between the common terminal (100) and the filter (12H). When the filter (12H) is regarded as a capacitance, the Q value of the capacitor (C2) in the first pass band is higher than the Q value of the capacitance in the first pass band.

An acoustic wave device includes a substrate, a multilayer film disposed on the substrate, a piezoelectric film disposed on the multilayer film, and a first excitation electrode and a second excitation electrode disposed on the piezoelectric film. The first excitation electrode has a plurality of first electrode fingers arranged with a first pitch p1 in a propagation direction of an acoustic wave. The second excitation electrode has a plurality of second electrode fingers arranged with a second pitch p2 in the propagation direction. The piezoelectric film is formed of a single crystal of LiTaO.sub.3 or a single crystal of LiNbO.sub.3. When t0 represents a thickness of the piezoelectric film, 1.15×p1≤p2, t0≤0.48×p1, and t0≥0.27×p2 are satisfied.

A multiplexer includes elastic wave filters with different pass bands, a common terminal to which an inductance element is serially connected in a connection path between an antenna element and the common terminal; and an inductance element. Among the elastic wave filters, a reception input terminal of a first reception filter is connected to the common terminal via the inductance element and is connected to a parallel resonator. Transmission output terminals of transmission filters and a reception input terminal of a second reception filter are connected to the common terminal, are connected to series resonators, and are not connected to parallel resonators.