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.

Acoustic resonators and filter devices. 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 spanning a cavity in the substrate. A conductor pattern formed is formed on the front surface of the piezoelectric plate, including an interdigital transducer (IDT) with interleaved fingers of the IDT on the diaphragm. The substrate and the piezoelectric plate are the same material.

Acoustic resonators and filter devices. 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 spanning a cavity in the substrate. A conductor pattern formed is formed on the front surface of the piezoelectric plate, including an interdigital transducer (IDT) with interleaved fingers of the IDT on the diaphragm. The substrate and the piezoelectric plate are the same material.

A radio frequency filter includes at least a first sub-filter and a second sub-filter connected in parallel between a first port and a second port. Each of the sub-filters has a piezoelectric plate having front and back surfaces, the back surface attached to a substrate, and portions of the piezoelectric plate forming diaphragms spanning respective cavities in the substrate. A conductor pattern is formed on the front surface of the plate, the conductor pattern includes interdigital transducers (IDTs) of a respective plurality of resonators, with interleaved fingers of each IDT disposed on a respective diaphragm of the plurality of diaphragms. A thickness of the portions of the piezoelectric plate of the first sub-filter is different from a thickness of the portions of the piezoelectric plate of the second sub-filter.

A radio frequency filter includes at least a first sub-filter and a second sub-filter connected in parallel between a first port and a second port. Each of the sub-filters has a piezoelectric plate having front and back surfaces, the back surface attached to a substrate, and portions of the piezoelectric plate forming diaphragms spanning respective cavities in the substrate. A conductor pattern is formed on the front surface of the plate, the conductor pattern includes interdigital transducers (IDTs) of a respective plurality of resonators, with interleaved fingers of each IDT disposed on a respective diaphragm of the plurality of diaphragms. A thickness of the portions of the piezoelectric plate of the first sub-filter is different from a thickness of the portions of the piezoelectric plate of the second sub-filter.

A cavity structure of a bulk acoustic resonator and a manufacturing process. The cavity structure comprises a substrate and a cavity formed on the substrate, a support layer is arranged on the substrate to form the cavity in a surrounding manner, a release channel in communication with the cavity is formed above the substrate in a same layer with the cavity, and the release channel extends, in parallel to the substrate, in a peripheral area of the cavity. There is no need to manufacture a release hole, which simplifies the manufacturing process of the resonator, thereby avoiding weakening the performance of the resonator due to damage to the structure of the piezoelectric layer around the electrode layer when manufacturing the release hole.

A cavity structure of a bulk acoustic resonator and a manufacturing process. The cavity structure comprises a substrate and a cavity formed on the substrate, a support layer is arranged on the substrate to form the cavity in a surrounding manner, a release channel in communication with the cavity is formed above the substrate in a same layer with the cavity, and the release channel extends, in parallel to the substrate, in a peripheral area of the cavity. There is no need to manufacture a release hole, which simplifies the manufacturing process of the resonator, thereby avoiding weakening the performance of the resonator due to damage to the structure of the piezoelectric layer around the electrode layer when manufacturing the release hole.

Methods for forming a film bulk acoustic resonator (FBAR) are provided. In the method, formation of several mutually overlapped and hence connected sacrificial material layers above and under a resonator sheet facilitates the removal of the sacrificial material layers. Cavities left after the removal overlap at a polygonal area with non-parallel sides. This reduces the likelihood of boundary reflections of transverse parasitic waves causing standing wave resonance in the FBAR, thereby enhancing its performance in parasitic wave crosstalk. Further, according to the disclosure, the FBAR is enabled to be integrated with CMOS circuitry and hence exhibits higher reliability.

Methods for forming a film bulk acoustic resonator (FBAR) are provided. In the method, formation of several mutually overlapped and hence connected sacrificial material layers above and under a resonator sheet facilitates the removal of the sacrificial material layers. Cavities left after the removal overlap at a polygonal area with non-parallel sides. This reduces the likelihood of boundary reflections of transverse parasitic waves causing standing wave resonance in the FBAR, thereby enhancing its performance in parasitic wave crosstalk. Further, according to the disclosure, the FBAR is enabled to be integrated with CMOS circuitry and hence exhibits higher reliability.

The invention provides a planarization method, which can make the local flatness of the product to be processed more uniform. The product has a cavity filled with oxide and includes a first electrode layer, a piezoelectric layer and a second electrode layer superposed on the cavity. The first electrode layer covers the cavity and includes a first inclined face around the first electrode layer, and the piezoelectric layer covers the first electrode layer and is arranged on the first electrode layer. The planarization method includes: depositing a passivation layer on the second electrode layer and etching the passivation layer completely until the thickness of the passivation layer is reduced to the required thickness.