A multiplexer includes a first filter, a second filter, a combining wiring line that provides a combination point at which an input or an output of each of the first filter and the second filter is connected to each other, an antenna terminal to connect the multiplexer to an antenna, an antenna wiring line connected at one end to the antenna terminal and connected at the other end to the combining wiring line, a matching terminal to which a matching inductor to provide matching between the antenna and the multiplexer is to be connected, and a matching wiring line to be connected at one end to the matching terminal and connected at the other end to the combining wiring line.

Aspects of this disclosure relate to a surface acoustic wave assembly that includes a first surface acoustic wave filter, a second surface acoustic wave filter, and a thermally conductive sheet configured to dissipate heat from the first surface acoustic wave filter in an area corresponding to the second surface acoustic wave filter. The thermally conductive sheet can be thinner than a piezoelectric layer of the first surface acoustic wave filter. Related radio frequency modules and methods are disclosed.

A filter module (20) includes a filter circuit (22) that includes switches (221SW and 224SW), a pass band of the filter circuit (22) being switched in accordance with switching between ON and OFF of the switches (221SW and 224SW); and an impedance matching circuit (21) that is disposed in at least one of a preceding stage and a subsequent stage of the filter circuit (22) and that includes a switch (212SW), an element value for achieving impedance matching being switched in the impedance matching circuit (21) in accordance with switching between ON and OFF of the switch (212SW). The switches (221SW and 224SW) and the switch (212SW) synchronize with each other regarding timing of switching between ON and OFF.

An acoustic wave device includes: a first substrate including a terminal located on a lower surface thereof; a second substrate including an acoustic wave element located on a lower surface thereof and mounted on the first substrate so that the element faces the first substrate; first bumps located between the first and second substrates, located between a first side of the first substrate and the element, and not connected to the element and the terminal; second bumps located between the first and second substrates, located between a second side facing the first side and the element, and not connected to the element and/or the terminal; and third bumps located between the first and second substrates, located only in a region located closer to the second side than the first bumps are and closer to the first side than the second bumps are, and connecting the element and the terminal.

A duplexer included in a radio frequency module is used in a communication band in which the transmit band in a single communication band includes a first transmit band and a second transmit band overlapping each other and in which the receive band in the single communication band includes a first receive band and a second receive band overlapping each other. A transmit filter unit in the duplexer uses, as a pass band, a fixed frequency band including the first transmit band and the second transmit band. A receive filter unit of the duplexer uses, as a pass band, a fixed frequency band including the first receive band and the second receive band.

An elastic wave apparatus includes a multilayer substrate, first through fourth band pass filters, an antenna terminal, and first and second inductors. The multilayer substrate includes first through sixth wiring layers. The first through fourth band pass filters are disposed on the multilayer substrate and are connected to a common node. The antenna terminal is connected to an antenna and also to the common node. The first inductor is connected to the antenna terminal. The second inductor is connected between the first band pass filter and the common node. The first inductor is disposed on the fourth and fifth wiring layers. The second inductor is disposed on the second and third wiring layers which are different from the fourth and fifth wiring layers. The first and second inductors overlap each other at least partially as viewed from above.

A multiplexer includes: first and second substrate respectively having first and second surfaces facing each other across an air gap; a first filter including first resonators located on the first surface and connected between a common terminal and a first terminal; a second filter including second resonators located on the second surface and connected between the common terminal and a second terminal, a first resonator connected in series between the common terminal and the first terminal and closest to the common terminal overlapping with a second resonator connected in series between the common terminal and the second terminal and closest to the common terminal, first resonators other than the first resonator closest to the common terminal not overlapping with the second resonators, second resonators other than the second resonator closest to the common terminal not overlapping with the first resonators.

A wafer-level chip-scale package includes a body, a conductive via passing through the body, a contact bump formed at a lower portion of the body and in electrical connection with a lower end of the conductive via, a piezoelectric substrate directly bonded to an upper end of the conductive via, and a cavity defined between a portion of the body and the piezoelectric substrate.

A communication module includes: a first substrate having a first surface; a second substrate having a second surface, the second surface facing the first surface across an air gap; a first filter located on the first surface, a passband of the first filter being either one of a transmit band and a receive band of a first band, the first band being a frequency division duplex band; and a second filter located on the second surface, at least a part of the second filter overlapping with at least a part of the first filter in a stacking direction in which the first substrate and the second substrate are stacked, a passband of the second filter being at least one of a transmit band and a receive band of a second band, the second band differing from the first band.

Aspects of this disclosure relate to a surface acoustic wave device that includes a thermally conductive layer configured to dissipate heat of the surface acoustic wave device. The surface acoustic wave device includes a piezoelectric layer and an interdigital transducer electrode on the piezoelectric layer. The thermally conductive layer can be thinner than the piezoelectric layer. Related radio frequency modules and wireless communication devices are disclosed.