Examples described herein provide selective filtering by a network device for continuous 5 GHz and 6 GHz operation. Examples may include receiving, by the network device, a first signal in a 5 GHz band, and generating, by the network device, a second signal in a 6 GHz band. Examples may include selecting, by the network device, a first filter or a second filter to be applied the first signal in the 5 GHz band, wherein the first filter allows a lower frequency band to pass than the second filter in the 5 GHz band, selecting, by the network device, a third filter or a fourth filter to be applied to the second signal in the 6 GHz band, wherein the third filter allows a lower frequency band to pass than the fourth filter in the 6 GHz band, and simultaneously applying, by the network device, the selected first or second filter to the first signal and the selected third or fourth filter to the second signal.

A BAW resonance device, a filter device and an RF front-end device are provided. The BAW resonance device comprises a first passive part including a first substrate and a first heat-dissipation layer located over the first substrate; a first active part including a first piezoelectric layer, a first electrode layer and a second electrode layer, wherein the first piezoelectric layer is located over the first passive part and has a first side and a second side opposite to the first side, the first passive part is located on the first side, the first electrode layer is also located on the first side and is disposed between the first passive part and the first piezoelectric layer, and the second electrode layer is located on the second side; and a first cavity located on the first side and disposed between the first passive part and the first piezoelectric layer, wherein at least one part of the first electrode layer is located on or in the first cavity. The first heat-dissipation layer can improve or flexibly adjust the heat-dissipation performance of the SAW resonance device.

A multiplexer includes acoustic wave filters that are electrically connected to a common connection terminal. In a first transmission-side filter of the acoustic wave filters, a series arm resonator closest to the common connection terminal includes acoustic wave resonators that are electrically connected in series and capacitance elements that are electrically connected between at least one of signal paths electrically connecting the acoustic wave resonators to each other and a reference terminal.

Aspects of this disclosure relate to a radio frequency system with an antenna, a radio frequency amplifier, and parallel acoustic wave filters. The parallel acoustic wave filters can each be a band pass filter having a passband and resonator area. The passbands of the parallel acoustic filters can be overlap in an overlap band. One of the parallel acoustic wave filters can have a smaller resonator area than another of the parallel acoustic wave filters.

An acoustic wave device includes an IDT electrode laminated on a piezoelectric substrate and defining a first resonator, and an IDT electrode laminated on the piezoelectric substrate and defining a second resonator. The first and second resonators are connected in parallel or in series. The IDT electrode of the first resonator includes an electrode layer including an epitaxial film and the IDT electrode of the second resonator includes an electrode layer including a non-epitaxial film.

A BAW resonance device comprises a first layer including a cavity located on a first side, a first electrode having a first end located in the cavity and a second end contacting with the first layer, a second layer located on the first side, and a second electrode located on the second layer above the cavity, wherein the first electrode and the second electrode are located on two sides of the second layer. The first electrode comprises a first electrode layer and a second electrode layer, and the second electrode layer and the second layer are located on two sides of the first electrode layer. The second electrode comprises a third electrode layer and a fourth electrode layer, and the second layer and the fourth electrode layer are located on two sides of the third electrode layer. Thus, the electrical resistance is lowered and the electrical losses are reduced.

An acoustic wave device includes a piezoelectric layer, a pair of comb-shaped electrodes disposed on a first surface of the piezoelectric layer, each of the pair of comb-shaped electrodes including electrode fingers that excite an acoustic wave, a support substrate disposed at a second surface side of the piezoelectric layer, and having protruding portions and/or recessed portions on a first surface, which is closer to the piezoelectric layer, of the support substrate, each of the protruding portions and/or the recessed portions having a shape in which each of left and right side surfaces has linear slopes inclined at different angles with respect to the first surface of the piezoelectric layer in a cross-sectional view, and a second insulating layer located between the piezoelectric layer and the support substrate and disposed on the third surface, on which the protruding portions and/or the recessed portions are formed, of the support substrate.

RF filtering circuitry comprises a first node, a second node, and a series signal path between the first node and the second node. A number of acoustic resonators are coupled to one or more of the first node and the second node via the series signal path. A first one of the acoustic resonators is associated with a first quality factor and a first electromechanical coupling coefficient. A second one of the acoustic resonators is associated with a second quality factor and a second electromechanical coupling coefficient. The first quality factor is different from the second quality factor and the first electromechanical coupling coefficient is different from the second electromechanical coupling coefficient.

A filter includes a series resonator including a first piezoelectric layer and first electrodes, and a parallel resonator including a second piezoelectric layer and second electrodes. Each of the first and second piezoelectric layers is a monocrystalline lithium niobate layers, has an X-axis orientation in a planar direction, and has a thickness direction in a direction obtained by a 105° rotation of a +Z-axis orientation toward a +Y-axis orientation. The first electrodes face each other across the first piezoelectric layer to form a first resonance region and are extracted from the first resonance region in a direction substantially parallel to the X-axis orientation of the first piezoelectric layer. The second electrodes face each other across the second piezoelectric layer to form a second resonance region and are extracted from the second resonance region in a direction substantially orthogonal to the X-axis orientation of the second piezoelectric layer.

A radio frequency (RF) extractor includes: a first bandpass filter electrically connected between a shared antenna port and a first RF port, disposed in a first chip, and having a first passband; a second bandpass filter electrically connected between the shared antenna port and a second RF port, and disposed in a second chip, and having a second passband; a first notch filter electrically connected to the shared antenna port, disposed in the first chip, and having a first stopband partially overlapping the first passband; and a second notch filter electrically connected to the shared antenna port, disposed in the second chip, and having a second stopband partially overlapping the second passband.