A substrate for a surface acoustic wave device is constituted of a piezoelectric material and includes a first surface on which a surface acoustic wave propagates, and a second surface located opposite to the first surface. The second surface has an arithmetic mean roughness (Ra) of 0.2 μm to 0.4 μm, and there is satisfied either of the relationship between the arithmetic mean roughness (Ra) and mean spacing (S) of local peaks of Ra/S≥11, and the relationship between the arithmetic mean roughness (Ra) and mean spacing (Sm) of irregularities of Ra/Sm≥6.7. Further, the second surface has a maximum height (Rmax) of 2.5 μm to 4.5 μm, and there is satisfied either of the relationship between the maximum height (Rmax) and mean spacing (S) of local peaks of Rmax/S≥130, and the relationship between the maximum height (Rmax) and mean spacing (Sm) of irregularities of Rmax/Sm≥80.

An acoustic wave filter includes a substrate and a piezoelectric layer over the substrate. First acoustic wave resonators are disposed over the piezoelectric layer and arranged in series along a first branch, and second acoustic wave resonators are disposed over the piezoelectric layer, arranged in parallel, and connected to the first branch and to ground. The first and second acoustic wave resonators include an interdigital transducer electrode interposed between a pair of reflectors. A layer of negative temperature coefficient of frequency dielectric material is disposed over one or more of the second plurality of acoustic wave resonators to control the temperature coefficient of frequency and improve temperature stability of the acoustic wave filter.

Heat dissipating characteristics of an acoustic wave filter is improved. A high frequency module includes a mounting substrate, an acoustic wave filter, a resin layer, and a shield layer. The mounting substrate has a first main surface and a second main surface that face each other. The acoustic wave filter is arranged near the first main surface of the mounting substrate. The resin layer is arranged on the first main surface of the mounting substrate and covers an outer peripheral surface of the acoustic wave filter. The shield layer covers the resin layer and the acoustic wave filter. The shield layer is in contact with a second main surface of the acoustic wave filter that is far from the mounting substrate.

A high-frequency module includes a module substrate including an internal wiring pattern, and a SAW filter including a piezoelectric substrate, an electrode pattern on the piezoelectric substrate, a support surrounding the electrode pattern, and a cover on the support covering the electrode pattern to define a hollow space together with the support and the piezoelectric substrate. The module substrate, the cover, and the piezoelectric substrate are disposed in this order in a perpendicular or substantially perpendicular direction with respect to the module substrate, and a shield electrode is provided on a surface of the cover that faces the module substrate or on a surface of the cover that faces the piezoelectric substrate.

A combined acoustic wave device package is provided comprising: a first substrate having a bulk acoustic wave (BAW) resonator formed thereon; a second substrate having a surface acoustic wave (SAW) resonator formed thereon; and at least one bonding element connecting the first substrate and second substrate. A method for forming such a combined acoustic wave device package is also provided. A radio frequency (RF) device comprising such a combined acoustic wave device package, and a wireless device comprising an antenna and a such a combined acoustic wave device package are also provided.

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.

An acoustic wave resonator includes: a piezoelectric substrate; and a pair of grating electrodes that is formed on the piezoelectric substrate, one of the pair of grating electrodes including a plurality of first electrode fingers having electric potentials equal to each other, another of the pair of grating electrodes including a plurality of second electrode fingers having electric potentials that differ from the electric potentials of the plurality of first electrode fingers and are equal to each other, two second electrode fingers of the plurality of second electrode fingers being located between at least a pair of adjacent first electrode fingers of the plurality of first electrode fingers, Pg differing from λ/4 where λ represents a wavelength of an acoustic wave excited by the plurality of first electrode fingers and the plurality of second electrode fingers and Pg represents a distance between centers of the two second electrode fingers.

Aspects of this disclosure relate to an acoustic wave device that includes high velocity layers on opposing sides of a piezoelectric layer. A low velocity layer can be positioned between the piezoelectric layer and one of the high velocity layers, in which the low velocity layer has a lower acoustic velocity than the high velocity layers. The acoustic wave device can be configured to generate a boundary acoustic wave such that acoustic energy is concentrated at a boundary of the piezoelectric layer and the low velocity layer.

An SAW device 1 includes a piezoelectric substrate 13, an IDT electrode 5 on a first major surface 3a of the piezoelectric substrate 13, a capacitance element 31 which is located on the first major surface 3a and is connected to the IDT electrode 5, and a cover 9 which is superimposed only on the capacitance element 31 between the IDT electrode 5 and the capacitance element 31.