A multiplexer includes acoustic wave filters that are electrically connected to a common connection terminal. In a first transmission-side filter of the acoustic wave filters, a series arm resonator closest to the common connection terminal includes acoustic wave resonators that are electrically connected in series and capacitance elements that are electrically connected between at least one of signal paths electrically connecting the acoustic wave resonators to each other and a reference terminal.

A multiplexer includes a common terminal, a first terminal, a second terminal, a first filter device including acoustic wave resonators including series resonators and parallel resonators, an inductor provided between an acoustic wave resonator and the first terminal, and a second filter device. The first filter device further includes a first ground terminal to which a parallel resonator is electrically connected, a second ground terminal to which the parallel resonators are electrically connected, and a wiring provided between the inductor and an acoustic wave resonator. In the first filter device, the wiring is electrically connected to the first ground terminal, and the first ground terminal is not connected to the second ground terminal.

A multiplexer includes a common terminal, a first terminal, a second terminal, a first filter device including acoustic wave resonators including series resonators and parallel resonators, an inductor provided between an acoustic wave resonator and the first terminal, and a second filter device. The first filter device further includes a first ground terminal to which a parallel resonator is electrically connected, a second ground terminal to which the parallel resonators are electrically connected, and a wiring provided between the inductor and an acoustic wave resonator. In the first filter device, the wiring is electrically connected to the first ground terminal, and the first ground terminal is not connected to the second ground terminal.

An acoustic wave device includes a piezoelectric substrate and an IDT electrode including electrode fingers. A portion of the IDT electrode in which the electrode fingers overlap with each other in a propagation direction of an acoustic wave is an intersecting region. The intersecting region includes a central region on a center side in an extending direction of the electrode fingers, and a first region and a second region located on respective sides of the central region in the extending direction of the electrode fingers. In the central region, a dielectric film is provided between the electrode fingers, and the dielectric film does not overlap with at least a portion of the electrode fingers when seen in plan view.

An acoustic wave device includes a piezoelectric substrate, a first interdigital transducer electrode on the piezoelectric substrate, and a first reflector and a second reflector. The first interdigital transducer electrode, the first reflector, and the second reflector each include a plurality of electrode fingers. At least one of the first interdigital transducer electrode, the first reflector, and the second reflector has a nonuniform duty ratio area where three successive electrode fingers in an acoustic wave propagation direction all have different duty ratios.

A longitudinally coupled resonator acoustic wave filter including IDT electrodes including a first IDT electrode and a second IDT electrode, and first and second reflectors, in which the IDT electrodes have respective hot-side comb-shaped electrodes and respective ground-side comb-shaped electrodes, the hot-side comb-shaped electrodes of the first IDT electrodes are electrically connected to at least one of the first and second reflectors, the second IDT electrodes are between the IDT electrode and the first reflector and between the IDT electrode and the second reflector respectively, the hot-side comb-shaped electrodes of the IDT electrodes are connected to one of an input end and an output end, and the hot-side comb-shaped electrodes of the IDT electrodes are connected to the other of the input end and the output end.

A longitudinally coupled resonator acoustic wave filter including IDT electrodes including a first IDT electrode and a second IDT electrode, and first and second reflectors, in which the IDT electrodes have respective hot-side comb-shaped electrodes and respective ground-side comb-shaped electrodes, the hot-side comb-shaped electrodes of the first IDT electrodes are electrically connected to at least one of the first and second reflectors, the second IDT electrodes are between the IDT electrode and the first reflector and between the IDT electrode and the second reflector respectively, the hot-side comb-shaped electrodes of the IDT electrodes are connected to one of an input end and an output end, and the hot-side comb-shaped electrodes of the IDT electrodes are connected to the other of the input end and the output end.

An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate, and a functional element on the piezoelectric layer. The support substrate and the piezoelectric layer each have a rectangular or substantially rectangular shape in plan view from a direction normal to the support substrate. At least one corner portion of the piezoelectric layer has a curved shape or a polygonal shape.

Certain aspects of the present disclosure provide a surface acoustic wave (SAW) device with one or more intermediate layers for reduced self-heating and methods for fabricating such a SAW device. One example SAW device generally includes a piezoelectric layer and an interdigital transducer (IDT) disposed above the piezoelectric layer. The IDT generally includes a first electrode having a first busbar and a first plurality of fingers. The first electrode generally includes a first copper layer disposed above the piezoelectric layer, a first intermediate layer disposed above the first copper layer, the first intermediate layer comprising a different material than the first copper layer, and a second copper layer disposed above the first intermediate layer.

A circuit module includes a mounting substrate including a conductor wiring, an elastic wave element provided in or on a main surface of the mounting substrate, an electric element provided in or on the main surface, the electric element being different from the elastic wave element, and an insulating resin portion provided in or on the main surface to cover the elastic wave element and the electric element. The elastic wave element and the electric element are connected to each other by the conductor wiring. A height of the elastic wave element is about 0.28 mm or less, which is less than that of the electric element. The thickness of the resin portion in a region in which the resin portion covers the elastic wave element is greater than the thickness of the resin portion in a region in which the resin portion covers the electric element.