A filter device includes a first series line, one or more first parallel lines extending from the first series line, two or more first series IDT electrodes on the first series line, and one or more first parallel IDT electrodes on the one or more first parallel lines. At least one of the two or more first series IDT electrodes is a first-type electrode. A dielectric layer is between the first-type electrode and a substrate. At least one of the two or more first series IDT electrodes except the first-type electrode and the one or more first parallel IDT electrodes is a second-type electrode directly contacting the substrate. A first series IDT electrode of the two or more first series IDT electrodes that has a largest pitch of electrode fingers is the first-type electrode.

A surface acoustic wave resonator comprises a multi-layer piezoelectric substrate including a carrier substrate, a layer of a first dielectric material disposed on the carrier substrate, and a layer of piezoelectric material disposed on the layer of the first dielectric material, interdigital transducer electrodes disposed on the layer of piezoelectric material and including interleaved electrode fingers, and a layer of a second dielectric material disposed on a central interleaved region of the interleaved electrode fingers, gap regions of the interdigital transducer electrodes being either free of the layer of the second dielectric material or having a thinner layer of the second dielectric material than the central interleaved region to reduce spurious signals in an admittance curve of the surface acoustic wave resonator.

An acoustic wave device, a method of manufacture of the same, and a radio frequency filter including the same. The acoustic wave device comprises a multilayer piezoelectric substrate (MPS) including a layer of piezoelectric material having a lower surface disposed on an upper surface of a layer of a dielectric material having a lower surface disposed on an upper surface of a carrier substrate. An interdigital transducer (IDT) is disposed on the multilayer piezoelectric substrate and includes an active region configured to generate an acoustic wave. First and second high impedance portions are included within the multilayer piezoelectric substrate, the first and second high impedance portions each positioned outside the active region of the interdigital transducer and extending in the direction of propagation of the acoustic wave to be generated by the interdigital transducer. The first and second high impedance portions reduce side leakage and suppress transverse modes.

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.

Aspects of this disclosure relate to a radio frequency system with an antenna, a radio frequency amplifier, and parallel acoustic wave filters. The parallel acoustic wave filters can each be a band pass filter having a passband and resonator area. The passbands of the parallel acoustic filters can be overlap in an overlap band. One of the parallel acoustic wave filters can have a smaller resonator area than another of the parallel acoustic wave filters.

A multiplexer includes a transmission-side filter electrically connected to a common terminal and a transmission input terminal, and a transmission-side filter electrically connected to the common terminal and a transmission input terminal. The transmission-side filter includes a plurality of series arm resonators and a plurality of parallel arm resonators. Capacitance elements are respectively electrically connected in parallel to the series arm resonator and the parallel arm resonator, which are connected most proximately to the common terminal. IDT electrodes of a series arm resonator and a parallel arm resonator connected most proximately to the common terminal do not include a thinning electrode, and others of the series arm resonators and the parallel arm resonators include thinning electrodes.

A front end radio frequency (RF) module including one or more first filter circuits configured to implement a front end function by filtering first signals communicated between one or more first antenna and a transceiver and one or more second filter circuits configured to implement at least a portion of an additional network function within the front end RF module by filtering second signals communicated between one or more second antennas and the transceiver.

A multimode longitudinally coupled surface acoustic wave resonator is disclosed. The multimode longitudinally coupled surface acoustic wave resonator can include a first interdigital transducer electrode that is positioned over a piezoelectric layer. The first interdigital transducer electrode includes fingers having a first pitch. The multimode longitudinally coupled surface acoustic wave resonator can also include first and second sets of reflectors that are positioned over the piezoelectric layer. The first and second sets of reflectors include a first number of reflectors having a second pitch and a second number of reflectors having a third pitch, respectively. The first pitch is greater than the second pitch. The multimode longitudinally coupled surface acoustic wave resonator can further include a second interdigital transducer electrode that is positioned over the piezoelectric layer and between the first interdigital transducer electrode and the first set of reflectors. The second interdigital transducer electrode includes fingers having a fourth pitch.

An acoustic wave device includes an acoustic wave element substrate, filter electrodes on a first surface of the acoustic wave element substrate, a first insulator layer covering a second surface of the acoustic wave element substrate, and a second insulator layer laminated on the first insulator layer and sandwiching the first insulator layer between the second insulator layer and the acoustic wave element substrate. The products of propagation speeds of an acoustic wave in those layers and densities of those layers satisfy a predetermined relationship.