A high-frequency apparatus includes a first device and a second device, and a mounting substrate on which the first and second devices are mounted. At least the second device is an acoustic wave device including a piezoelectric substrate and a functional element. The first device and the second device are adjacent to or in a vicinity of each other on the mounting substrate. A coefficient of linear expansion of a substrate of the first device is lower than a coefficient of linear expansion of the mounting substrate, and a coefficient of linear expansion of the piezoelectric substrate of the second device is higher than the coefficient of linear expansion of the mounting substrate.

The present disclosure provides a method of preparing a radio frequency filter, including: a substrate; a supporting electrode protruded on a front surface of the substrate; and a thin film structure formed on the substrate and spaced with the substrate by the supporting electrode. An end surface of a top end of the supporting electrode is in sealing contact with a front surface of the thin film structure.

A crystal oscillator (101) includes: a piezoelectric resonator plate (2) on which a first excitation electrode and a second excitation electrode are formed; a first sealing member (3) covering the first excitation electrode of the piezoelectric resonator plate (2); a second sealing member (4) covering the second excitation electrode of the piezoelectric resonator plate (2); and an internal space (13) formed by bonding the first sealing member (3) to the piezoelectric resonator plate (2) and by bonding the second sealing member (4) to the piezoelectric resonator plate (2), so as to hermetically seal a vibrating part including the first excitation electrode and the second excitation electrode of the piezoelectric resonator plate (2). An electrode pattern (371) including a mounting pad for wire bonding is formed on an outer surface (first main surface (311)) of the first sealing member (3).

An RF filter system including a plurality of BAW resonators arranged in a circuit, the circuit including a serial configuration of resonators and a parallel shunt configuration of resonators, the circuit having a circuit response corresponding to the serial configuration and the parallel configuration of the plurality of bulk acoustic wave resonators including a transmission loss from a pass band having a bandwidth from 5.490 GHz to 5.835 GHz. Resonators include a support member with a multilayer reflector structure; a first electrode including tungsten; a piezoelectric film including aluminum scandium nitride; a second electrode including tungsten; and a passivation layer including silicon nitride. At least one resonator includes at least a portion of the first electrode located within a cavity region defined by a surface of the support member.

A bulk-acoustic resonator module includes: a module substrate; a bulk-acoustic resonator connected to the module substrate by a connection terminal and disposed spaced apart from the module substrate; and a sealing portion sealing the bulk-acoustic resonator. The bulk-acoustic resonator includes a resonating portion disposed opposite to an upper surface of the module substrate. A space is disposed between the resonating portion and the upper surface of the module substrate.

A high frequency module includes a mounting substrate, an acoustic wave filter, a protection member, a resin layer, and a shield layer. The acoustic wave filter is mounted on a first main surface of the mounting substrate. The protection member is disposed on a main surface of the acoustic wave filter that is far from the mounting substrate. The resin layer is disposed on the first main surface of the mounting substrate and covers an outer peripheral surface of the acoustic wave filter and an outer peripheral surface of the protection member. The shield layer covers the resin layer and the protection member. The protection member is in contact with both the acoustic wave filter and the shield layer. The acoustic wave filter includes a piezoelectric substrate. A main surface of the piezoelectric substrate that is far from the mounting substrate is in contact with the protection member.

Heat dissipating characteristics of an acoustic wave filter is improved. A high frequency module includes a mounting substrate, an acoustic wave filter, a resin layer, and a shield layer. The mounting substrate has a first main surface and a second main surface that face each other. The acoustic wave filter is arranged near the first main surface of the mounting substrate. The resin layer is arranged on the first main surface of the mounting substrate and covers an outer peripheral surface of the acoustic wave filter. The shield layer covers the resin layer and the acoustic wave filter. The shield layer is in contact with a second main surface of the acoustic wave filter that is far from the mounting substrate.

An RF integrated circuit device can includes a substrate and a High Electron Mobility Transistor (HEMT) device on the substrate including a ScAlN layer configured to provide a buffer layer of the HEMT device to confine formation of a 2DEG channel region of the HEMT device. An RF piezoelectric resonator device can be on the substrate including the ScAlN layer sandwiched between a top electrode and a bottom electrode of the RF piezoelectric resonator device to provide a piezoelectric resonator for the RF piezoelectric resonator device.

A system for a wireless communication infrastructure using single crystal devices. The wireless system can include a controller coupled to a power source, a signal processing module, and a plurality of transceiver modules. Each of the transceiver modules includes a transmit module configured on a transmit path and a receive module configured on a receive path. The transmit modules each include at least a transmit filter having one or more filter devices, while the receive modules each include at least a receive filter. Each of these filter devices includes a single crystal acoustic resonator device formed with a thin film transfer process with at least a first electrode material, a single crystal material, and a second electrode material. Wireless infrastructures using the present single crystal technology perform better in high power density applications, enable higher out of band rejection (OOBR), and achieve higher linearity as well.

A semiconductor package structure includes a plurality of transducer devices, a cap structure, at least one redistribution layer (RDL) and a protection material. The transducer devices are disposed side by side. Each of the transducer devices has at least one transducing region, and includes a die body and at least one transducing element. The die body has a first surface and a second surface opposite to the first surface. The transducing region is disposed adjacent to the first surface of the die body. The transducing element is disposed adjacent to the first surface of the die body and within the transducing region. The cap structure covers the transducing region of the transducer device to form an enclosed space. The redistribution layer (RDL) electrically connects the transducer devices. The protection material covers the transducer devices.