A radio-frequency module includes a mount board, an electronic component, an external connection terminal, and an acoustic wave filter. The mount board has a first principal surface and a second principal surface facing each other. The electronic component is arranged on the first principal surface of the mount board. The external connection terminal is arranged on the second principal surface of the mount board. The acoustic wave filter is arranged on the second principal surface of the mount board. The acoustic wave filter is a bare-chip acoustic wave filter. The radio-frequency module is suppressed in height along a thickness of the mount board.

The invention provides a filter device, an RF front-end device and a wireless communication device. The filter device comprises a substrate, at least one resonance device, a passive device and a connector, wherein the at least one resonance device has a first side and a second side opposite to the first side, the substrate is located on the first side, and the passive device is located on the second side. The at least one resonance device is connected to the passive device through the connector. The RF filter device formed by integrating the resonance device (such as an SAW resonance device or a BAW resonance device) and the passive device (such as an IPD) in one die can broaden the passband width, has a high out-of-band rejection, and occupies less space in an RF front-end chip.

The invention provides a filter device, an RF front-end device and a wireless communication device. The filter device comprises a substrate, at least one resonance device, a passive device and a connector, wherein the at least one resonance device has a first side and a second side opposite to the first side, the substrate is located on the first side, and the passive device is located on the second side. The at least one resonance device is connected to the passive device through the connector. The RF filter device formed by integrating the resonance device (such as an SAW resonance device or a BAW resonance device) and the passive device (such as an IPD) in one die can broaden the passband width, has a high out-of-band rejection, and occupies less space in an RF front-end chip.

Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

A filter includes: one or more series resonators connected in series between an input terminal and an output terminal, the one or more series resonators including a series resonator located closest to the output terminal, the series resonator located closest to the output terminal having a resonant frequency that is 99.6% or less of or 102.2% or greater of a center frequency of a passband; one or more parallel resonators connected in parallel between the input terminal and the output terminal; and an inductor connected in parallel to the series resonator located closest to the output terminal.

In a surface acoustic wave filter, a parallel arm resonator includes an IDT electrode and reflectors. Comb-shaped electrodes of the IDT electrode each include a busbar electrode and electrode fingers connected thereto, and are arranged so that the electrode fingers of the respective comb-shaped electrodes are alternately located in a propagation direction of a surface acoustic wave. The reflectors are provided on both sides of the IDT electrode portion in the propagation direction of the surface acoustic wave so that reflector electrode fingers are parallel or substantially parallel to the electrode fingers. A distance between the electrode finger and the reflector electrode finger which are proximate to each other is about 10% or more and about 20% or less of a main pitch of the electrode fingers.

An acoustic wave device includes a support substrate, a piezoelectric layer provided on the support substrate, at least a pair of comb-shaped electrodes provided on the piezoelectric layer, each of the comb-shaped electrodes including a plurality of electrode fingers, and an insulating layer provided between the support substrate and the piezoelectric layer, the insulating layer having, in at least a part thereof, a plurality of void regions of which extending directions are different from each other when viewed from a thickness direction of the support substrate, a width in the corresponding extending direction of each of the void regions being longer than a width in a direction orthogonal to the corresponding extending direction when viewed from the thickness direction of the support substrate.

A multiplexer includes a first matching circuit having one end connected to a common terminal; a first filter that has one end connected to the other end of the first matching circuit and the other end connected to a first terminal; a second matching circuit having one end connected to the common terminal; a second filter that has one end connected to the other end of the second matching circuit and the other end connected to a second terminal; and a third filter that has one end connected to the common terminal and the other end connected to a third terminal. The first matching circuit includes a first inductor connected on a first signal path in the first matching circuit. The second matching circuit includes a second inductor connected between a second signal path in the second matching circuit and ground.

A multiplexer includes a first matching circuit having one end connected to a common terminal; a first filter that has one end connected to the other end of the first matching circuit and the other end connected to a first terminal; a second matching circuit having one end connected to the common terminal; a second filter that has one end connected to the other end of the second matching circuit and the other end connected to a second terminal; and a third filter that has one end connected to the common terminal and the other end connected to a third terminal. The first matching circuit includes a first inductor connected on a first signal path in the first matching circuit. The second matching circuit includes a second inductor connected between a second signal path in the second matching circuit and ground.

An elastic wave resonator including a piezoelectric substrate and an IDT electrode, the IDT electrode includes a first electrode finger and a second electrode finger arranged next to the first electrode finger; when W.sub.1 is the width of the first electrode finger, W.sub.2 is the width of the second electrode finger, and L is a pitch or an electrode finger center distance between the first electrode finger and the second electrode finger; a metallization ratio (W.sub.1/L) of the first electrode finger is smaller than a metallization ratio (W.sub.2/L) of the second electrode finger; a sum (W.sub.1/L+W.sub.2/L) of the metallization ratio of the first electrode finger and the metallization ratio of the second electrode finger is between about 0.65 and about 1.00 inclusive, and a ratio (W.sub.2/W.sub.1) between a width of the first electrode finger and a width of the second electrode finger is between about 1.12 and about 2.33 inclusive, or W.sub.1/L+W.sub.2/L is larger than about 1.00, and W.sub.2/W.sub.1 is between about 1.40 and about 2.34 inclusive.