An elastic wave filter device includes a piezoelectric film, a high acoustic velocity support substrate in which an acoustic velocity of a propagating bulk wave is larger than an acoustic velocity of a main mode elastic wave propagating in the piezoelectric film, and IDT electrodes in contact with the piezoelectric film. A serial arm resonator and a parallel arm resonator are defined by the IDT electrodes such that, a direction in which tips of first and second electrode fingers are connected defines a tilt angle with respect to a propagation direction of elastic waves excited by the IDT electrodes. A tilt angle of the serial arm resonator is different from a tilt angle of the parallel arm resonator.

An acoustic wave filter device includes a substrate, first and second acoustic impedance layers, a piezoelectric layer, first and second interdigital transducer electrodes, an input terminal, an output terminal, ground terminals, a series arm circuit, and a parallel arm circuits. The first interdigital transducer electrode at least partially overlaps the first acoustic impedance layer in the plan view. The second interdigital transducer electrode at least partially overlaps the second acoustic impedance layer in the plan view. The series arm circuit is provided on a first path connecting the input terminal and the output terminal and includes the first and second interdigital transducer electrodes. A conductive layer in the first acoustic impedance layer and a conductive layer in the second acoustic impedance layer are electrically insulated from each other.

A filter device includes a longitudinally coupled resonator elastic wave filter that includes IDT electrodes including low acoustic velocity regions in outer side portions of center regions of the IDT electrodes and high acoustic velocity regions in outer side portions of the low acoustic velocity regions in a direction orthogonal or substantially orthogonal to an elastic wave propagation direction, and defines and functions as a first bandpass filter, and elastic wave resonators that are electrically connected to the longitudinally coupled resonator elastic wave filter.

Acoustic resonator devices, filter devices, and methods of fabrication are disclosed. An acoustic resonator includes a substrate having a surface and a single-crystal piezoelectric plate having front and back surfaces. The back surface is attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm that spans a cavity in the substrate. An interdigital transducer (IDT) is formed on the front surface of the single-crystal piezoelectric plate such that interleaved fingers of the IDT are disposed on the diaphragm. The IDT is configured to excite a primary acoustic mode in the diaphragm in response to a radio frequency signal applied to the IDT. The interleaved fingers extend at an oblique angle to an Z crystalline axis of the piezoelectric plate.

An acoustic wave device includes: a piezoelectric substrate; and an IDT formed on the piezoelectric substrate, wherein an anisotropy coefficient is positive, an overlap region where electrode fingers of the IDT overlap each other includes a center region and an edge region, the electrode fingers in the center and edge regions are continuously formed, the electrode finger in the edge region is inclined with respect to the electrode finger in the center region so that a pitch in a width direction of the electrode finger in the edge region is greater than a pitch in a width direction of the electrode finger in the center region, and an angle between the width direction in the center region and a crystal axis orientation of the piezoelectric substrate is less than an angle between the width direction in the edge region and the crystal axis orientation.

An acoustic wave device includes a substrate, a first resonator, a second resonator, and a shared reflector. The second resonator is adjacent to the first resonator and has different frequency characteristics different than the first resonator. The first resonator includes a first interdigital transducer electrode. The second resonator includes a second interdigital transducer electrode. The shared reflector has frequency characteristics that are the same as both frequency characteristics of the first resonator and frequency characteristics of the second resonator or between the frequency characteristics of the first resonator and the frequency characteristics of the second resonator. a higher-order mode frequency of the first resonator and a higher-order mode frequency of the second resonator coincides. When the number of electrode fingers of the shared reflector is even, an electrode finger facing the shared reflector in the first interdigital transducer electrode and an electrode finger facing the shared reflector in the second interdigital transducer electrode have the same polarity. When the number of electrode fingers of the shared reflector is odd, an electrode finger facing the shared reflector in the first interdigital transducer electrode and an electrode finger facing the shared reflector in the second interdigital transducer electrode have opposite polarities.

An acoustic wave device is disclosed. The acoustic wave device can include a multilayer piezoelectric substrate and an interdigital transducer electrode over the multilayer piezoelectric substrate. The interdigital transducer electrode includes a first layer and a second layer over the first layer. The interdigital transducer electrode has a tilt angle of at least 12 degrees. The acoustic wave device being configured to generate a surface acoustic wave having a wavelength L.

An acoustic wave device includes a piezoelectric substrate including a piezoelectric layer, and resonator electrodes on the piezoelectric substrate and each including electrode fingers and an IDT electrode. The resonator electrodes include first and second resonator electrodes. At least one of the first and second resonator electrodes includes a curved resonator electrode in which the electrode fingers have a curved shape in plan view. The first and second resonator electrodes face each other, and a resonator electrode is positioned on a convex side, in a direction in which the electrode fingers are arranged, of a portion including the curved shape of the curved resonator electrode.