Electroacoustic devices with a capacitive element and methods for fabricating such electroacoustic devices. An example method includes forming an acoustic device above a first region of a substrate, and forming a capacitive element above a second region of the substrate and adjacent to the acoustic device. The forming of the capacitive element may include forming a protective layer above the substrate where a first portion of the protective layer is above the second region of the substrate and a second portion of the protective layer is above the first region of the substrate, forming a dielectric region above the protective layer, and forming an electrode above the dielectric region. The dielectric region may include a different material than the protective layer.

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.

A filter (22A) includes: a series arm circuit (11) that is connected between an input/output terminal (22m) and an input/output terminal (22n); and a parallel arm circuit (12) that is connected between a node (x1), which is on a path that connects the input/output terminal (22m) and the input/output terminal (22n), and ground. The parallel arm circuit (12) includes a parallel arm resonator (22p) and an impedance circuit (13) that is serially connected to the parallel arm resonator (22p). The impedance circuit (13) includes a first impedance element, which is one of an inductor and a capacitor, a second impedance element, which is the other of an inductor and a capacitor, and a switch (22SW) that is serially connected to the second impedance element. A first series circuit (14) comprising of the second impedance element and the switch (22SW) is connected in parallel with the first impedance element.

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.

A radio-frequency module includes a mount board, an acoustic wave filter, a metal block, a resin layer, and a shield layer. The mount board has a first principal surface and a second principal surface opposite to each other, and has a ground layer. The acoustic wave filter is mounted on the first principal surface of the mount board. The metal block is disposed on the first principal surface of the mount board, and is connected to the ground layer. The resin layer is disposed on the first principal surface of the mount board, and covers the periphery of the acoustic wave filter and the periphery of the metal block. The shield layer covers the principal surface, which is on the opposite side to the mount board side, of the acoustic wave filter, the resin layer, and the metal block. The metal block is in contact with the shield layer.

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.

A filter device includes a port, a reference potential part, at least one filter, a signal line, a first inductor, and at least one second inductor. A signal is input through the port, and/or a signal is output through the port. The reference potential part is placed at a reference potential. The at least one filter filters a signal. The signal line connects the port to the at least one filter. The first inductor is at least part of the signal line. The second inductor forms a connection between the signal line and the reference potential part. The first inductor and the at least one second inductor are inductively coupled to each other.

A filter device includes a first filter including series resonators and parallel resonators, a first inductor connected in parallel between a first terminal and the first filter, a second inductor provided in series between the first filter and a second terminal, and a third inductor provided in series in a channel connecting the parallel resonator and ground, the third inductor is incorporated in a multilayer substrate, the first filter is mounted on a main surface of the multilayer substrate and incorporated in a filter chip, and the first inductor and the second inductor are chip inductors including coil conductors and are mounted on the main surface of the multilayer substrate beside the filter chip so as to be adjacent to each other and such that coil axes thereof are orthogonal or substantially orthogonal to each other.

A first filter is a hybrid filter including an acoustic wave filter, a plurality of first inductors, and a plurality of first capacitors. A high frequency module further includes a metal electrode layer covering at least part of a resin layer and at least part of an outer peripheral surface of a mounting substrate. Among a plurality of inductors including the plurality of first inductors of the first filter and a plurality of second inductors of a second filter, at least one inductor (the second inductor) is a circuit element including a conductor pattern portion formed in the mounting substrate. The shortest distance between the outer peripheral surface of the mounting substrate and a signal terminal (a third signal terminal) connected to the circuit element is longer than the shortest distance between the outer peripheral surface of the mounting substrate and the circuit element.