An acoustic wave device includes: a support substrate; a first piezoelectric substrate bonded to a first principal surface of the support substrate, the first piezoelectric substrate being a single crystal substrate, a first acoustic wave resonator located on an opposite surface of the first piezoelectric substrate from a surface to which the support substrate is bonded, the first acoustic wave resonator including an IDT; a second piezoelectric substrate bonded to a second principal surface of the support substrate opposite from the first principal surface, the second piezoelectric substrate being a single crystal substrate; and a second acoustic wave resonator located on an opposite surface of the second piezoelectric substrate from a surface to which the support substrate is bonded, the second acoustic wave resonator including an IDT.

An acoustic wave device includes: a first substrate that includes a first acoustic wave filter located on an upper surface of the first substrate; a second substrate that is flip-chip mounted on the upper surface of the first substrate through a bump, and includes a second acoustic wave filter on a lower surface of the second substrate, the lower surface of the second substrate facing the upper surface of the first substrate across an air gap; and a shield electrode that is supported by the upper surface of the first substrate, and is located between at least a part of the first acoustic wave filter and at least a part of the second acoustic wave filter through the air gap.

An acoustic wave component is disclosed. The acoustic wave component can include a bulk acoustic wave resonator and a surface acoustic wave device. The bulk acoustic wave resonator can include a first portion of a ceramic substrate, a first piezoelectric layer positioned on the ceramic substrate, and electrodes positioned on opposing sides of the first piezoelectric layer. The surface acoustic wave device can include a second portion of the ceramic substrate, a second piezoelectric layer positioned on the ceramic substrate, and an interdigital transducer electrode on the second piezoelectric layer.

A filter includes: a piezoelectric substrate; one or more series resonators that are located on the piezoelectric substrate and are connected in series between an input terminal and an output terminal; at least one series resonator that is connected between a first node and a second node, is included in the one or more series resonators, and includes a reflector that is grounded, the first node and the second node being located between the input terminal and the output terminal; and a cancel line that is connected in parallel with the at least one series resonator between the first node and the second node, and cancels a signal outside a passband propagating through the at least one series resonator from the first node to the second node.

A surface acoustic wave filter is disclosed. The surface acoustic wave filter includes a substrate, and first and second surface acoustic wave filter structures disposed on first and second main surfaces of the substrate, respectively. The first surface acoustic wave filter structure includes a first piezoelectric layer a plurality of first surface acoustic wave resonators formed on a top surface of the first piezoelectric layer, and a first wiring layer connecting the first surface acoustic wave resonators to each other. The second surface acoustic wave filter structure includes a second piezoelectric layer, a plurality of second surface acoustic wave resonators formed on a bottom surface of the second piezoelectric layer, and a second wiring layer connecting the second surface acoustic wave resonators to each other. A plurality of through electrodes extends through the substrate, the first piezoelectric layer, and the second piezoelectric layer. A circuit including the first surface acoustic wave resonators and the first wiring layer on the top surface of the first piezoelectric layer forms at least one first radio frequency filter, and a circuit including the plurality of second surface acoustic wave resonators and the second wiring layer on the bottom surface of the second piezoelectric layer forms at least one second radio frequency filter. The at least one first radio frequency filter and the at least one second radio frequency filter belong to different frequency bands.

A multiplexer device includes a single die, at least three acoustic filters and at least one antenna port arranged on the single die, and a shunt inductance connected between each of the at least one antenna port and ground. Each acoustic filter includes one of a transmit or receive filter corresponding to a predetermined radio frequency band. The at least one antenna port is connected to at least one antenna, respectively, where each of the at least one antenna port is further connected to at least one acoustic filter arranged on the single die, and is configured to pass RF signals corresponding to the predetermined RF band of the connected at least one acoustic filter. The shunt inductance provides impedance matching between each of the at least one antenna port and each of the at least one acoustic filter connect to the at least one antenna port.

An acoustic wave device includes: a first piezoelectric substrate; a first IDT that includes a plurality of first electrode fingers and is located on a first surface of the first piezoelectric substrate; a second piezoelectric substrate that is located above the first surface; and a second IDT that is located on a second surface of the second piezoelectric substrate, and includes a plurality of second electrode fingers that are non-parallel to the plurality of first electrode fingers, the second surface of the second piezoelectric substrate facing the first surface across an air gap.

An electronic device includes: a first substrate including a first functional element located on an upper surface of the first substrate; a second substrate that is flip-chip mounted on the upper surface of the first substrate through a bump, and includes a second functional element located on a lower surface of the second substrate; and a sealing member that is located on the upper surface of the first substrate, surrounds the second substrate in plan view, is not located between the first substrate and the second substrate, seals the first functional element and the second functional element so that the first functional element and the second functional element are located across an air gap.

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 device includes a first piezoelectric substrate including a first principal surface and a second principal surface, a second piezoelectric substrate including a first principal surface and a second principal surface and with a greater thickness than that of the first piezoelectric substrate, and ground terminals located on the second principal surface of the first piezoelectric substrate. The first principal surface of the first piezoelectric substrate and the first principal surface of the second piezoelectric substrate are joined to face each other. On the first principal surface of the first piezoelectric substrate, a first elastic wave filter is located. On the first principal surface of the second piezoelectric substrate, a second elastic wave filter is located. The out-of-band attenuation of the first elastic wave filter is greater than the out-of-band attenuation of the second elastic wave filter.