A multiplexer includes filters on one principal surface of a mounting substrate and having mutually different frequency bands, and an inductance element which is incorporated in the mounting substrate and one end of which is connected to one end of the filter. The other end of the inductance element and one end of each of the filters, are connected to each other at a common connection point. The inductance element is defined by spiral wiring conductors disposed in first and second wiring layers provided in an inner layer of the mounting substrate. The mounting substrate includes third and fourth wiring layers which are adjacent to the first and second wiring layers, and in which no ground pattern is provided in a portion corresponding to a formation region of the inductance element.

A multiplexer includes filters on one principal surface of a mounting substrate and having mutually different frequency bands, and an inductance element which is incorporated in the mounting substrate and one end of which is connected to one end of the filter. The other end of the inductance element and one end of each of the filters, are connected to each other at a common connection point. The inductance element is defined by spiral wiring conductors disposed in first and second wiring layers provided in an inner layer of the mounting substrate. The mounting substrate includes third and fourth wiring layers which are adjacent to the first and second wiring layers, and in which no ground pattern is provided in a portion corresponding to a formation region of the inductance element.

An acoustic wave resonator includes: a piezoelectric substrate that is a lithium tantalate substrate or a lithium niobate substrate and has a thickness of 20 m or less; a support substrate that has an upper surface bonded with a lower surface of the piezoelectric substrate And is a glass substrate mainly composed of silicon oxide; a plurality of electrode fingers that are located on an upper surface of the piezoelectric substrate, excite an acoustic wave, and include a metal film mainly composed of at least one of Cr, Mo, and W.

In a filter device, a transversal elastic wave filter, which defines a delay element, is connected in parallel with a band pass filter. The transversal elastic wave filter has the same amplitude characteristic as and the opposite phase to the band pass filter at a desired frequency inside an attenuation range of the band pass filter. When a wavelength determined by an electrode finger period of IDTs and is denoted by , the distance between the first IDT and the second IDT of the elastic wave filter is about 12 or less.

The present disclosure relates to Surface Acoustic Wave (SAW) devices, including those configured as resonators. The SAW devices will generally include a piezoelectric layer, an interface structure, and an interdigitated transducer. The piezoelectric layer is formed from a piezoelectric material and may be provided by a piezoelectric film that resides over a carrier substrate or a piezoelectric substrate. The piezoelectric layer will have a top surface. The interdigitated transducer has a first pattern and resides over the top surface of the piezoelectric layer. The interface structure has a second pattern that generally corresponds to the first pattern of the interdigitated transducer and resides between the top surface of the piezoelectric layer and the interdigitated transducer.

A multiplexer includes filters on one principal surface of a mounting substrate and having mutually different frequency bands, and an inductance element which is incorporated in the mounting substrate and one end of which is connected to one end of the filter. The other end of the inductance element and one end of each of the filters, are connected to each other at a common connection point. The inductance element is defined by spiral wiring conductors disposed in first and second wiring layers provided in an inner layer of the mounting substrate. The mounting substrate includes third and fourth wiring layers which are adjacent to the first and second wiring layers, and in which no ground pattern is provided in a portion corresponding to a formation region of the inductance element.

An acoustic wave filter includes: a piezoelectric substrate; series resonators connected in series and located on the piezoelectric substrate, each of the series resonators including first electrode fingers that are arranged with a first duty ratio and excite an acoustic wave; parallel resonators connected in parallel and located on the piezoelectric substrate, each of the parallel resonators including second electrode fingers that are arranged with a second duty ratio and excite an acoustic wave, the second duty ratio in at least one parallel resonator being less than the first duty ratio in at least one series resonator; and a dielectric film that has a temperature coefficient of elastic modulus that is opposite in sign to that of the piezoelectric substrate, is located on the piezoelectric substrate so as to cover the first and second electrode fingers, has a film thickness greater than those of the first and second electrode fingers.

An acoustic wave resonator includes: an IDT located on a piezoelectric substrate, including comb-shaped electrodes facing each other and including electrode fingers and a bus bar connecting the electrode fingers; a first silicon oxide film located on the electrode fingers in an overlap region where the electrode fingers overlap and having a film thickness in a part of edge regions, which correspond to both ends of the overlap region, equal to or less than that in a center region sandwiched between the edge regions; and a second silicon oxide film located on the electrode fingers, containing an element slowing an acoustic velocity in a silicon oxide film when being added to the silicon oxide film, having a concentration of the element greater than that in the first silicon oxide film, and having a film thickness in a part of the edge regions greater than that in the center region.

Aspects of this disclosure relate to an acoustic wave device that includes an acoustic obstacle disposed between canceling circuits coupled to one or more acoustic wave filters. The canceling circuits can cancel frequency components within different frequency bands. The acoustic obstacle can reduce acoustic coupling between the canceling circuits by scattering and/or absorbing acoustic energy.

A wave separator includes an n number (n being a natural number of 3 or larger) of band pass filters having an n number or larger of mutually different pass bands, and a common terminal. For a first of the band pass filters that is one of a band pass filter having a center frequency of a pass band at a lowest side and a band pass filter having a center frequency of a pass band at a highest side and that has a larger or equal difference in a center frequency of a pass band from an adjacent band pass filter as compared with the other band pass filter satisfies a predetermined configuration for a second band pass filter having a pass band adjacent to the first band pass filter.