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.

Acoustic wave resonators are disclosed that include a piezoelectric layer and an interdigital transducer electrode over the piezoelectric layer. The interdigital transducer electrode has a rotation angle and a tilt angle. The rotation angle and the tilt angle can together increase a figure of merit of the acoustic wave device. The rotation angle and the tilt angle can both be non-zero.

An acoustic wave device including series arm resonators including a first IDT electrode and parallel arm resonators including a second IDT electrode, in the first IDT electrode, a first envelope obliquely extends with respect to the acoustic wave propagation direction, and a second envelope obliquely extends with respect to the acoustic wave propagation direction, the second IDT electrode includes a central region, a first low acoustic velocity region in which an acoustic velocity is lower than an acoustic velocity in the central region, a second low acoustic velocity region in which an acoustic velocity is lower than the acoustic velocity in the central region, a first high acoustic velocity region in which an acoustic velocity is higher than the acoustic velocity in the central region, and a second high acoustic velocity region in which an acoustic velocity is higher than the acoustic velocity in the central region.

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.

According to one configuration, an acoustical device includes a piezoelectric substrate and at least one curved electrode. Material on a surface of the piezoelectric substrate defines boundaries of a resonance region. The curved electrode is disposed on the piezoelectric substrate in the resonance region and is operable to receive a voltage input signal through a first conductive waveguide. When present, the voltage input signal causes generation and conveyance of acoustical waves from the curved electrode into the resonance region. The acoustical device optionally includes a second curved electrode in the resonance region, which converts the acoustical waves present in the resonance region to an output voltage signal.

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.

An acoustic wave device includes a piezoelectric substrate a reverse-velocity surface of which is convex, an interdigital transducer electrode disposed on the piezoelectric substrate, and mass addition films stacked above the interdigital transducer electrode. The interdigital transducer electrode includes a central region, first and second edge regions, first and second gap regions located outside the first and second edge regions, first and second inner busbar regions, and first and second outer busbar regions. The mass addition films are stacked in at least the first and second edge regions and the first and second inner busbar regions.

An SAW device includes a piezoelectric substrate, an IDT electrode on a first major surface of the piezoelectric substrate, a capacitance element which is located on the first major surface and is connected to the IDT electrode, and a cover which is superimposed only on the capacitance element between the IDT electrode and the capacitance element.

A first filter of a multiplexer has a ladder filter structure defined by 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 smaller than the third slant angle.

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.