A laterally coupled multi-mode monolithic filter includes: a substrate; a piezoelectric film formed on the substrate; a ground electrode formed on a first surface of the piezoelectric film; and signal electrodes formed on a second surface of the piezoelectric film and arranged in parallel to each other, the second surface being opposite to the first surface, each of the signal electrodes including a first electrode finger and a second electrode finger, wherein the first electrode finger and the second electrode finger have different electric potentials; adjacent signal electrodes of the signal electrodes are at a distance from each other, the distance being greater than a pitch of the first electrode finger and the second electrode finger.

A surface acoustic wave resonator arrangement comprises a piezoelectric substrate (100) and a surface acoustic wave resonator (110) which includes an interdigital transducer (111,112) disposed on the piezoelectric substrate (100). A trench (13 0) is disposed within the piezoelectric substrate (100) facing the resonator (110). Trench (130) causes reflected waves (143,144) in response to waves (141,142) leaking from the surface acoustic wave resonator. Trench (130) is configured such that the reflected acoustic waves (143,144) achieve phases at the edge (115) of the resonator (110) such that the accumulated phases of all the reflected waves received at edge (115) is zero or substantially zero, thereby avoiding constructive interference of the reflected waves with the acoustic waves resonating in the resonator. Thereby undesired acoustic coupling between resonators or influence of waves reflected at edges of the piezoelectric substrate or dicing lines is reduced.

A method of making an acoustic wave device includes forming or providing a substrate, forming or providing a functional layer over at least a portion of the substrate, forming or providing a piezoelectric layer over at least a portion of the functional layer, and forming or providing an interdigital transducer electrode over the piezoelectric layer. Forming or providing the piezoelectric layer includes removing a portion of the piezoelectric layer so that the piezoelectric layer has an outer edge spaced inward of an outer edge of the substrate, and so that the outer edge of the piezoelectric layer is tapered at an angle relative to a surface of the substrate to thereby reduce an acoustic reflection magnitude at said outer edge of the piezoelectric layer.

An example integrated circuit package includes an acoustic wave resonator, the acoustic wave resonator including a Fresnel surface. In some examples, the Fresnel surface includes a plurality of recessed features and/or protruding features at different locations on the Fresnel surface, each of the plurality of features to confine main mode acoustic energy from a respective portion of the Fresnel surface in a central portion of the acoustic wave resonator.

An elastic wave device includes a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate. The IDT electrode includes a busbar electrode extending in an elastic wave propagation direction and electrode fingers connected to the busbar electrode and extending in a direction perpendicular or substantially perpendicular to the elastic wave propagation direction. The piezoelectric substrate includes a groove extending along the elastic wave propagation direction. The groove is provided on a side across the busbar electrode in the perpendicular or substantially perpendicular direction from a side at which the electrode fingers are located.

An example integrated circuit package includes an acoustic wave resonator, the acoustic wave resonator including a Fresnel surface. In some examples, the Fresnel surface includes a plurality of recessed features and/or protruding features at different locations on the Fresnel surface, each of the plurality of features to confine main mode acoustic energy from a respective portion of the Fresnel surface in a central portion of the acoustic wave resonator.

Acoustic wave resonators having Fresnel features are disclosed. An example integrated circuit package includes an acoustic wave resonator, the acoustic wave resonator including a Fresnel surface. In some examples, the Fresnel surface includes a plurality of recessed features and/or protruding features at different locations on the Fresnel surface, each of the plurality of features to confine main mode acoustic energy from a respective portion of the Fresnel surface in a central portion of the acoustic wave resonator.

An elastic wave device includes a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate. The IDT electrode includes a busbar electrode extending in an elastic wave propagation direction and electrode fingers connected to the busbar electrode and extending in a direction perpendicular or substantially perpendicular to the elastic wave propagation direction. The piezoelectric substrate includes a groove extending along the elastic wave propagation direction. The groove is provided on a side across the busbar electrode in the perpendicular or substantially perpendicular direction from a side at which the electrode fingers are located.

Acoustic wave resonators having Fresnel features are disclosed. An example integrated circuit package includes an acoustic wave resonator, the acoustic wave resonator including a Fresnel surface. In some examples, the Fresnel surface includes a plurality of recessed features and/or protruding features at different locations on the Fresnel surface, each of the plurality of features to confine main mode acoustic energy from a respective portion of the Fresnel surface in a central portion of the acoustic wave resonator.

A surface acoustic wave resonator includes an IDT that is disposed on a quartz crystal substrate of Euler angles (1.51.5, 117142, ) and excites a surface acoustic wave resonant in an upper part of a stop-band of the IDT, and inter-electrode finger grooves that are acquired by depressing the substrate located between electrode fingers configuring the IDT. The wavelength of the surface acoustic wave, the depth of the inter-electrode finger grooves, the line occupancy ratio of the IDT, and the film thickness of the electrode fingers of the IDT are set in correspondence with one another.