Radio frequency (RF) filtering devices, and particularly compensation structures for RF filtering devices are disclosed. Representative RF filtering devices are described that include compensation structures configured to adjust, reduce, or cancel leakage signals within the RF filtering devices, thereby providing improved isolation. Compensation structures may include surface acoustic wave (SAW) devices having multiple interdigital transducers (IDT) that are longitudinally coupled between two reflective structures. Different IDTs of a SAW device may be electrically connected to an RF filtering device, and at least one IDT of the SAW device may comprise an electrically floating electrode that provides the ability to further tune acoustic waves. Depending on the application, the compensation structure may be electrically connected to different portions of the RF filtering device. In certain embodiments, the RF filtering device is an RF duplexing device.

Radio frequency (RF) filtering devices, and particularly compensation structures for RF filtering devices are disclosed. Representative RF filtering devices are described that include compensation structures configured to adjust, reduce, or cancel leakage signals within the RF filtering devices, thereby providing improved isolation. Compensation structures may include surface acoustic wave (SAW) devices having multiple interdigital transducers (IDT) that are longitudinally coupled between two reflective structures. Different IDTs of a SAW device may be electrically connected to an RF filtering device, and at least one IDT of the SAW device may comprise an electrically floating electrode that provides the ability to further tune acoustic waves. Depending on the application, the compensation structure may be electrically connected to different portions of the RF filtering device. In certain embodiments, the RF filtering device is an RF duplexing device.

A surface acoustic wave (SAW) structure is provided. The SAW structure includes an interdigital transducer (IDT) over a first surface of a piezoelectric structure. The IDT includes a first electrode finger and a second electrode finger arranged in parallel along a first direction and at least partially overlapped with each other. The SAW structure also includes a first embedded acoustic reflector in the piezoelectric structure on one side of the IDT along a second direction, and a second embedded acoustic reflector in the piezoelectric structure on another side of the IDT along the second direction. A first surface of each of the first embedded acoustic reflector and the second embedded acoustic reflector is coplanar with the first surface of the piezoelectric structure. A second surface of each of the first embedded acoustic reflector and the second embedded acoustic reflector is located between the first surface and a second surface of the piezoelectric structure.

A surface acoustic wave filter package comprising a tapered interdigital transducer structure.

A surface acoustic wave (SAW) device includes a substrate; an interdigital transducer (IDT) having lead-out portions and arrays of interdigital electrodes formed on the substrate, wherein the interdigital electrodes includes central portions, end portions, and intermediate portions between the end portions and the lead-out portions, and a thickness of the interdigital electrodes at the end portions is greater than a thickness of the interdigital electrodes at the central portions and the intermediate portions, thereby forming protruding structures at the end portions of the interdigital electrodes; a protective layer formed on the protruding structures at the end portions of the interdigital electrodes; a first temperature compensation layer formed on the protective layer; a second temperature compensation layer formed on the first temperature compensation layer and on the central portions and the intermediate portions of the interdigital electrodes; and a passivation layer formed on the second temperature compensation layer.

A surface acoustic wave device comprising a base substrate, a piezoelectric layer and an electrode layer in between the piezoelectric layer and the base substrate, a comb electrode formed on the piezoelectric layer comprising a plurality of electrode means with a pitch p, defined asp=A, with A being the wavelength of the standing acoustic wave generated by applying opposite potentials to the electrode layer and comb electrode, wherein the piezoelectric layer comprises at least one region located in between the electrode means, in which at least one physical parameter is different compared to the region underneath the electrode means or fingers. A method of fabrication for such surface acoustic wave device is also disclosed. The physical parameter may be thickness, elasticity, doping concentration of Ti or number of protons obtained by proton exchange.

A method for fabricating a surface acoustic wave (SAW) device includes forming an interdigital transducer (IDT) having lead-out portions and arrays of interdigital electrodes on a substrate, wherein the interdigital electrodes include central portions, end portions, and intermediate portions between the end portions and the lead-out portions; forming a protective layer on the IDT; forming a first temperature compensation layer on the protective layer; forming openings in the first temperature compensation layer to expose portions of the protective layer on the central portions and the intermediate portions of the interdigital electrodes; and etching the exposed portions of the protective layer, and etching the central portions and the intermediate portions of the interdigital electrodes to a preset thickness, to form protruding structures at the end portions of the interdigital electrodes.

A filter device includes a series arm connecting input and output terminals. Parallel arms branch from the series arm to a ground terminal. The parallel arms include first and second parallel arms branching from portions of the series arm. The first and second parallel arm resonators are respectively provided in or on the first and second parallel arms. The parallel arm resonators each include an IDT electrode including electrode fingers. Each IDT electrode includes an overlap region. A number of pairs of electrode fingers of the IDT electrode in the first parallel arm resonator is greater than a number of pairs of electrode fingers of the IDT electrode in the second parallel arm resonator. An overlap width of the IDT electrode in the first parallel arm resonator is narrower than the overlap width of the IDT electrode in the second parallel arm resonator.

A filter device includes a piezoelectric substrate, a dielectric layer on the piezoelectric substrate, a first IDT electrode on the dielectric layer, a second IDT electrode positioned on the piezoelectric substrate in an area where the dielectric layer is not provided such that the first and second IDT electrodes are side by side in an acoustic wave propagation direction extending along a principal surface of the piezoelectric substrate, a first reflector on the dielectric layer and adjacent to the first IDT electrode on a side of the second IDT electrode, and a second reflector on the piezoelectric substrate and adjacent to the second IDT electrode on a side of the first IDT electrode. The dielectric layer includes an edge portion between the first and second reflectors in planar view seen from a stacking direction of the piezoelectric substrate and the dielectric layer.

A surface acoustic wave (SAW) device comprises a substrate and composite electrodes. The composite electrodes comprise a metal layer and a graphene layer. The SAW device may be used to satisfy requirements for the fifth generation (5G) mobile communication.