A high-frequency module (10) includes a laminated substrate formed by laminating a plurality of insulator layers, a first terminal (P1) and a second terminal (P2) provided on the laminated substrate, a filter (20) connected between the first terminal (P1) and the second terminal (P2), a matching circuit (40) connected between the first terminal (P1) and the filter (20), and an inductor (60) provided as a conductor pattern in or on the laminated substrate, and connected between the filter (20) and the ground. The matching circuit (40) includes a mounting circuit unit (41) provided as an individual component on the laminated substrate, and a layer circuit (42) provided as a conductor pattern in or on the laminated substrate. A layer circuit unit (42) is electromagnetically coupled to the inductor (60).

A bulk acoustic resonator operable in a bulk acoustic mode includes a resonator body mounted to a separate carrier that is not part of the resonator body. The resonator body includes a piezoelectric layer, a device layer, and a top conductive layer on the piezoelectric layer opposite the device layer. The piezoelectric layer is a single crystal of LiNbO.sub.3 cut at an angle of 130°±30°. A surface of the device layer opposite the piezoelectric layer is for mounting the resonator body to the carrier.

A vibration device includes a base including a semiconductor substrate and through electrodes that pass through the portion between first and second surfaces of the semiconductor substrate, and a vibrator fixed to the first surface via an electrically conductive joining member. The following components are placed at the second surface: an oscillation circuit that is electrically coupled to the vibrator via the through electrodes and generates an oscillation signal by causing the vibrator to oscillate, a temperature sensor circuit, a temperature compensation circuit that performs temperature compensation on the oscillation signal, and an output buffer circuit that outputs a clock signal based on the oscillation signal. Dsx1<Dbx1, a distance between the output buffer circuit and one of the through electrodes is Dbx1, a distance between the temperature sensor circuit and the other through electrode is Dsx1.

A vibration device includes a base including a semiconductor substrate and a through electrode passing through the portion between a first surface and a second surface of the semiconductor substrate, a vibrator placed at the side facing the first surface, and an external connection terminal provided at the side facing the second surface via an insulating layer. An oscillation circuit that is electrically coupled to the vibrator via the through electrode and generates an oscillation signal by causing the vibrator to oscillate, and an output buffer circuit that outputs a clock signal based on the oscillation signal are placed at the second surface. The clock signal from the output buffer circuit is outputted via the external connection terminal. The through electrode and the external connection terminal are arranged so as not to overlap with each other in a plan view viewed in the direction perpendicular to the first surface.

In a crystal oscillator, a crystal resonator and an IC chip are hermetically sealed in a package. The crystal resonator includes: a crystal resonator plate including a first excitation electrode formed on a first main surface, and a second excitation electrode, which makes a pair with the first excitation electrode, formed on a second main surface; a first sealing member covering the first excitation electrode of the crystal resonator plate; and a second sealing member covering the second excitation electrode of the crystal resonator plate. A vibrating part including the first excitation electrode and the second excitation electrode of the crystal resonator plate is hermetically sealed by bonding the first sealing member to the crystal resonator plate, and the second sealing member to the crystal resonator plate.

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 RF filter (BPF) with an increased bandwidth is provided. The filter comprises a half-lattice topology and a phase shifter (PS) comprising inductively coupled inductance elements in a parallel branch parallel to a first segment (S1) of a signal path (SP) between a first port (P1) and a second port (P2) of the filter.

A resonator device includes: a base including a semiconductor substrate; a resonator element; and a lid to be bonded to the base, the lid and the base forming a cavity for accommodating the resonator element. An integrated circuit is disposed at the semiconductor substrate, the integrated circuit including an oscillation circuit electrically coupled to the resonator element, a memory circuit configured to store a reference value of an output characteristic of the resonator element, and a determination circuit configured to compare a detection value of the output characteristic of the resonator element with the reference value and determine an airtight state inside the cavity based on a comparison result.

An electronic component includes an insulating surrounding member surrounding the electronic element while allowing a first surface of the electronic element to be exposed from a second surface of the surrounding member. A wiring board faces a third surface comprising the first and second surfaces. An insulating joining member is interposed between the third surface and the wiring board and joins the third surface and the wiring board together. A conductive bump, located between the third surface and the wiring board, electrically connects the electronic element and the wiring board. The joining member has a first through hole that overlaps a vibration region in the first surface in perspective plan view. The joining member has a second through hole that accommodates the bump. At least a portion of at least one of the first through hole or the second through hole overlaps the second surface in perspective plan view.

A SAW filter includes a substrate including a piezoelectric substrate, a transmission filter, and an additional resonator. The transmission filter is a ladder-type filter filtering signals from a transmission terminal and outputting the result to an antenna terminal. Further, the transmission filter includes one or more serial resonators and one or more parallel resonators which are connected in a ladder configuration on the piezoelectric substrate. An initial stage resonator is the serial resonator. The additional resonator includes an IDT electrode on the piezoelectric substrate. The IDT electrode is connected to the transmission terminal at a stage before the transmission filter and is connected to any of the one or more GND terminals. In the additional resonator, a resonance frequency and an antiresonance frequency are located outside of a passband of the transmission filter.