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.

An acoustic resonator package includes a substrate, a cap including a protrusion portion protruding toward the substrate, an acoustic resonator disposed between the substrate and the cap and including a first electrode, a piezoelectric layer, and a second electrode, a metal layer connected to one of the first electrode and the second electrode, and a conductive pad at least partially disposed between the protrusion portion and the metal layer and extending in a first direction different from a second direction in which the acoustic resonator faces the conductive pad.

Disclosed is a Bulk Acoustic Wave (BAW) filter structure with a conductive bridge forming an electrical loop with an electrode for reduced electrical losses. In exemplary aspects disclosed herein, the BAW filter structure includes a transducer with electrodes, a piezoelectric layer between the electrodes, and at least one conductive bridge offset from at least a portion of one of the electrodes by an insulating volume. The conductive bridge forms a first electrical loop between a medial end and a distal end of the electrode. Such a configuration reduces electrical resistance, heat resistance, and/or ohmic losses for improved electrical loss of the BAW filter structure.

There are disclosed acoustic resonators and radio frequency filter devices. A back surface of a single-crystal piezoelectric plate is attached to a surface of a substrate except for portions of the piezoelectric plate forming a plurality of diaphragms, each of which spans a respective cavity in the substrate. A conductor pattern is formed on the front surface, the conductor pattern including interdigital transducers (IDTs) of one or more pairs of sub-resonators, each pair consisting of two sub-resonators. The IDT of each sub-resonator includes interleaved fingers disposed on a respective diaphragm. The piezoelectric plate and the IDTs are configured such that respective radio frequency signals applied to each IDT excite respective shear primary acoustic modes in the respective diaphragms. The two sub-resonators of each pair of sub-resonators are positioned symmetrically about a central axis.

Aspects of this disclosure relate to bandpass filters with enhanced out of band rejection. The bandpass filters include a stage that is modified using a network of three inductors two of which are mutually coupled inductors. Related methods, radio frequency systems, radio frequency modules, and wireless communication devices are also disclosed.

An electronic filter comprises a high pass section (110) and a low pass section (120). The high pass section includes at least one filter stage of a series-connected acoustic resonator (111) and a parallel connected inductor (114). The low pass section comprises at least one filter stage including a series-connected inductor (121) and a parallel connected acoustic resonator (123). The filter is useful for a communication device covering the n79 5G band.

A ladder filter comprises a plurality of series arm bulk acoustic wave resonators electrically connected in series between an input port and an output port of the ladder filter and a plurality of shunt bulk acoustic wave resonators electrically connected in parallel between adjacent ones of the plurality of series arm bulk acoustic wave resonators and ground, at least one of the plurality of shunt bulk acoustic wave resonators including raised frame regions having a first width, at least one of the plurality of series arm bulk acoustic wave resonators having one of raised frame regions having a second width less than the first width or lacking raised frame regions.

A ladder filter comprises a plurality of series arm bulk acoustic wave resonators electrically connected in series between an input port and an output port of the ladder filter and a plurality of shunt bulk acoustic wave resonators electrically connected in parallel between adjacent ones of the plurality of series arm bulk acoustic wave resonators and ground, at least one of the plurality of shunt bulk acoustic wave resonators including raised frame regions having a first width, at least one of the plurality of series arm bulk acoustic wave resonators having one of raised frame regions having a second width less than the first width or lacking raised frame regions.

A bulk acoustic resonator comprises a membrane including a piezoelectric film having multiple layers of piezoelectric material. At least one of the multiple layers of piezoelectric material has a different dopant concentration than another of the multiple layers of piezoelectric material.

A bulk acoustic wave filter includes series resonators connected to a series arm, and parallel resonators connected to a parallel arm connected to the series arm. Two or more of the series resonators are disposed in parallel on the series arm, and each includes a substrate, a lower electrode on the substrate, a piezoelectric layer on the lower electrode, and an upper electrode on the piezoelectric layer, wherein, when an active region in which the lower electrode, the piezoelectric layer, and the upper electrode overlap each other is viewed from above, a centroid of the active region and a center of a rectangle defining an aspect ratio of the active region match each other, and when the active region is viewed from above, the active region has a shape of polygon symmetrical with respect to at least one axis passing through a center of the rectangle defining the aspect ratio.