Gallium nitride (GaN) integrated circuit technology with resonators is described. In an example, an integrated circuit structure includes a layer or substrate including gallium and nitrogen. A first plurality of electrodes is over the layer or substrate. A resonator layer is on the first plurality of electrodes, the resonator layer including aluminum and nitrogen. A second plurality of electrodes is on the resonator layer. Individual ones of the second plurality of electrodes are vertically over and aligned with corresponding individual ones of the first plurality of electrodes.

Apparatus and associated methods relate to forming an epitaxial layer of aluminum on an aluminum-nitride compound. The aluminum is epitaxially grown on the crystalline aluminum-nitride compound by maintaining temperature of a crystalline aluminum-nitride compound below a cluster-favoring temperature threshold within a vacuum chamber. Then, the crystalline aluminum-nitride compound is exposed to atoms of elemental aluminum for a predetermined time duration. The aluminum is epitaxially grown in this fashion for a predetermined time duration so as to produce a layer of epitaxial aluminum of a predetermined thickness. Such epitaxially-grown mono-crystalline aluminum has a lower resistivity than poly-crystalline aluminum.

Piston mode Lamb wave resonators are disclosed. A piston mode Lamb wave resonator can include a piezoelectric layer, such as an aluminum nitride layer, and an interdigital transducer on the piezoelectric layer. The piston mode Lamb wave resonator has an active region and a border region, in which the border region has a velocity with a lower magnitude than a velocity of the active region. The border region can suppress a transverse mode.

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.

An electrode structure of a resonator and a fabrication method for the electrode structure of the resonator are provided. The electrode structure includes a piezoelectric layer. An electrode metal layer, a dielectric layer, a protrusion/frame metal layer and an etching passivation layer are sequentially arranged above the piezoelectric layer. An air gap is formed between the dielectric layer and the protrusion/frame metal layer, and the air gap is located at an electrode edge. Through the air gap between the dielectric layer and the protrusion/frame metal layer above the piezoelectric layer, an electrode protrusion/frame structure of the resonator with an edge air gap is formed, which serves as an electrode part. When the resonator is working, through the air gap, a transverse sound wave can be reflected back to the resonator and be bound in a resonator body. This greatly increases the Q factor and working performance of the resonator.

Acoustic resonators, filters, and methods. An acoustic resonator includes a substrate, a piezoelectric plate, and a diaphragm including a portion of the piezoelectric plate spanning a cavity in a substrate. An interdigital transducer (IDT) on a front surface of the piezoelectric plate includes first and second sets of interleaved interdigital transducer (IDT) fingers extending from first and second busbars respectively. The interleaved IDT fingers extend onto the diaphragm. Overlapping portions of the interleaved IDT fingers define an aperture of the acoustic resonator. First and second dielectric strips are on the front surface of the piezoelectric plate. Each dielectric strip has a first portion under the IDT fingers in a respective margin of the aperture and a second portion extending into a gap between the respective margin and the respective busbar.

A multi-stage matching network filter circuit device. The device comprises bulk acoustic wave (BAW) resonator device having an input node, an output node, and a ground node. A first matching network circuit is coupled to the input node. A second matching network circuit is coupled to the output node. A ground connection network circuit coupled to the ground node. The first or second matching network circuit can include an inductive ladder network including a plurality of series inductors in a series configuration and a plurality of grounded inductors wherein each of the plurality of grounded inductors is coupled to the connection between each connected pair of series inductors. The inductive ladder network can include one or more LC tanks, wherein each of the one or more LC tanks is coupled between a connection between a series inductor and a subsequent series inductor, which is also coupled to a grounded inductor.

An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.

Acoustic resonators, filters, and methods. An acoustic resonator includes a substrate, piezoelectric plate, and a diaphragm comprising a portion of the piezoelectric plate spanning a cavity in a substrate. An interdigital transducer (IDT) on a front surface of the piezoelectric plate includes first and second sets of interleaved interdigital transducer (IDT) fingers extending from first and second busbars respectively. The interleaved IDT fingers are on the diaphragm. Overlapping portions of the interleaved IDT fingers define an aperture of the acoustic resonator. A first dielectric strip overlaps the IDT fingers in a first margin of the aperture and extends into a first gap between the first margin and the first busbar. A second dielectric strip overlaps the IDT fingers in a second margin of the aperture and extends into a second gap between the second margin and the second busbar.

An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.