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 multiplexer (1) includes a plurality of filters connected to a common terminal (110). The multiplexer (1) includes: a low-frequency filter (11L) that is formed of at least one surface acoustic wave resonator arranged between the common terminal (110) and the input/output terminal (120) and has a first pass band; a high-frequency filter (12H) that is connected between the common terminal (110) and the input/output terminal (130) and has a second pass band located at a higher frequency than the first pass band; and a capacitor (C.sub.B1) that is serially arranged in a connection path between the common terminal (110) and the low-frequency filter (11L). The Q value of the capacitor (C.sub.B1) in the second pass band is higher than the Q value in the second pass band of a capacitance obtained by treating the at least one surface acoustic wave resonator of the low-frequency filter (11L) as a capacitance.

An acoustic wave device includes in order a substrate, an acoustic reflection layer, a piezoelectric layer, an IDT electrode including a pair of comb electrodes, and wiring electrodes. The acoustic reflection layer includes a low Z dielectric layer, a high Z dielectric layer below the low Z dielectric layer and having an acoustic impedance higher than that of the low Z dielectric layer, and a metal layer above the low Z dielectric layer and having an acoustic impedance higher than that of the low Z dielectric layer. When the acoustic reflection layer is viewed in plan, in a region encompassing the IDT electrode and the wiring electrodes but no IDT electrodes other than the IDT electrode, an area including the metal layer is smaller than an area including the high Z dielectric layer.

A piezoelectric resonator device having a sandwich structure is provided, which can avoid gas generation with reduced size or height. A crystal resonator includes a crystal resonator plate, a first sealing member and a second sealing member. A sealing-member-side first bonding pattern and a sealing-member-side second bonding pattern, both to be bonded to the crystal resonator plate, are formed respectively on the first and second sealing members. On the crystal resonator plate, a resonator-plate-side first bonding pattern to be bonded to the first sealing member is formed on a first main surface and a resonator-plate-side second bonding pattern to be bonded to the second sealing member is formed on a second main surface. The sealing-member-side first bonding pattern is bonded to the resonator-plate-side first bonding pattern, and the sealing-member-side second bonding pattern is bonded to the resonator-plate-side second bonding pattern, both by diffusion bonding.

Aspects of the present disclosure provide three-dimensional (3D) through-glass-via (TGV) inductors for use in electronic devices. In some embodiments, a first portion of a 3D TGV inductor may be formed in a first wafer and a second portion of a 3D TGV may be formed in a second wafer. The first portion and second portion may be bonded together in a bonded wafer device thereby forming a larger inductor occupying relatively little wafer space on the first and the second wafers.

Aspects of this disclosure relate to a bulk acoustic wave device that includes a multi-layer raised frame structure. The multi-layer raised frame structure includes a first raised frame layer positioned between a first electrode and a second electrode of the bulk acoustic wave device. The first raised frame layer has a lower acoustic impedance than the first electrode. The first raised frame layer and the second raised frame layer overlap in an active region of the bulk acoustic wave device. Related filters, multiplexers, packaged modules, wireless communication devices, and methods are disclosed.

A BAW device includes a substrate, a first reflector, and at least two BAW transducers. The first reflector resides over the substrate and has a plurality of reflector layers. A first BAW transducer resides over a first section of the first reflector, has a first series resonance frequency, and has a first piezoelectric layer of a first thickness between a first top electrode and a first bottom electrode. The second BAW transducer resides over a second section of the first reflector, has a second series resonance frequency that is different than the first series resonance frequency, and has a second piezoelectric layer of a second thickness, which is different than the first thickness, between a second top electrode and a second bottom electrode.

A crystal controlled oscillator includes a crystal unit, an integrated circuit, and an insulating resin. The crystal unit contains a crystal vibrating piece resonating at a predetermined frequency. The integrated circuit places the crystal unit. The integrated circuit includes an oscillator circuit oscillating the crystal vibrating piece. The insulating resin is formed to cover the crystal unit on the integrated circuit.

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.

Aspects of the present disclosure provide three-dimensional (3D) through-glass-via (TGV) inductors for use in electronic devices. In some embodiments, a first portion of a 3D TGV inductor may be formed in a first wafer and a second portion of a 3D TGV may be formed in a second wafer. The first portion and second portion may be bonded together in a bonded wafer device thereby forming a larger inductor occupying relatively little wafer space on the first and the second wafers.