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.

There are disclosed acoustic resonators and method of fabricating acoustic resonators. An acoustic resonator includes a single-crystal piezoelectric plate having front and back surfaces, the back surface attached to a surface of a substrate except for portions of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. A conductor pattern on the front surface includes an interdigital transducer (IDT) with interleaved fingers of the IDT disposed on the diaphragm. A periodic array of holes is provided in the diaphragm.

A multiplexer includes a first reception-side filter and a second reception-side filter whose passband has frequencies higher than the first reception-side filter. The first reception-side filter includes a series arm resonator provided on a first path, and parallel arm resonators provided on a path electrically connecting the first path and ground. A direction connecting tips of a plurality of electrode fingers included in each resonator crosses an elastic wave propagating direction at a certain angle. The parallel arm resonator closest to a common connection terminal does not include third electrode fingers, and the other parallel arm resonators include third electrode fingers.

A first filter of a multiplexer includes a ladder filter structure of acoustic wave resonators. An imaginary line obtained by connecting second ends of electrode fingers included in one comb-shaped electrode among a pair of comb-shaped electrodes of each resonator intersects a reference line that is a straight line extending in an acoustic wave propagation direction. When an angle defined by the reference line and the imaginary line of a first series resonator is represented by a first slant angle, an angle defined by the reference line and the imaginary line of a parallel resonator is represented by a second slant angle, and an angle defined by the reference line and the imaginary line of acoustic wave resonators is represented by a third slant angle, at least one of the first slant angle and the second slant angle is larger than the third slant angle.

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.

An acoustic wave filter device includes a piezoelectric layer, a high-acoustic-velocity member, a low-acoustic-velocity film between the high-acoustic-velocity member and the piezoelectric layer, and first and second IDT electrodes on the piezoelectric layer to define acoustic wave resonators. An acoustic wave resonator of a series-arm resonator portion closest to an antenna end and/or an acoustic wave resonator of a parallel-arm resonator portion closest to the antenna end includes the first IDT electrode including first and second electrode fingers, and the remaining acoustic wave resonators include the second IDT electrode including third and fourth electrode fingers. In the first IDT electrode, a central area, first and second low-acoustic-velocity areas, and first and second high-acoustic-velocity areas extend along a direction perpendicular or substantially perpendicular to an acoustic wave propagating direction. First and second envelopes connecting the tips of the third and fourth electrode fingers of the second IDT electrode are inclined.

A multiplexer includes a first reception-side filter and a second reception-side filter whose passband has frequencies higher than the first reception-side filter. The first reception-side filter includes a series arm resonator provided on a first path, and parallel arm resonators provided on a path electrically connecting the first path and ground. A direction connecting tips of a plurality of electrode fingers included in each resonator crosses an elastic wave propagating direction at a certain angle. The parallel arm resonator closest to a common connection terminal does not include third electrode fingers, and the other parallel arm resonators include third electrode fingers.

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.

A filter including a piezoelectric substrate; a surface acoustic wave (SAW) device on the piezoelectric substrate and including unequally spaced interdigitated input and output transducer electrodes of unequal widths, wherein the input transducer electrodes are to convert an incoming radio frequency (RF) electrical signal into surface acoustic waves; a SAW propagation path between the input and output transducer electrodes; and a magnetostrictive film in the SAW propagation path to filter the surface acoustic waves that are at a ferromagnetic resonance frequency of the magnetostrictive film, wherein the output transducer electrodes are to convert the filtered surface acoustic waves into an outgoing electrical RF signal. The SAW device may operate in a wide-band pass configuration. The wide-band pass configuration result in a transmission of frequencies up to 60 dB. The magnetostrictive film may include a ferromagnetic material. The interdigitated input and output transducer electrodes may include unequal widths between adjacent electrodes.

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.