Aspects of this disclosure relate to a multiplexer with a hybrid acoustic passive filter. The multiplexer includes a plurality of filters configured to filter respective radio frequency signals, a shared filter coupled between each of the plurality of filters and a common node, and a radio frequency filter coupled to the common node. At least a first filter of the plurality of filters includes acoustic resonators and a non-acoustic passive component. Related multiplexers, wireless communication devices, and methods are disclosed.

An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate, functional electrodes on the piezoelectric layer, and first and second electrode films positioned on the piezoelectric layer to face each other and having different potentials from each other. A thickness of the piezoelectric layer in at least a portion of a first region overlapping the first electrode film in plan view is different from a thickness of the piezoelectric layer in at least a portion of a second region not overlapping the first electrode film in plan view.

A filter module has a first terminal, a second terminal, and at least one filter disposed along each signal path extending from the first terminal to the second terminal. The filter can include a plurality of series resonators and a plurality of shunt resonators disposed between the series resonators and a ground configured to enhance power ruggedness of the filter module. A matching circuit coupled to the filter performs impedance matching of the filter.

An RF filter system including a plurality of BAW resonators arranged in a circuit, the circuit including a serial configuration of resonators and a parallel shunt configuration of resonators, the circuit having a circuit response corresponding to the serial configuration and the parallel configuration of the plurality of bulk acoustic wave resonators including a transmission loss from a pass band having a bandwidth from 5.170 GHz to 5.835 GHz. Resonators include a support member with a multilayer reflector structure; a first electrode including tungsten; a piezoelectric film including aluminum scandium nitride; a second electrode including tungsten; and a passivation layer including silicon nitride. At least one resonator includes at least a portion of the first electrode located within a cavity region defined by a surface of the support member.

An RF filter system including a plurality of BAW resonators arranged in a circuit, the circuit including a serial configuration of resonators and a parallel shunt configuration of resonators, the circuit having a circuit response corresponding to the serial configuration and the parallel configuration of the plurality of bulk acoustic wave resonators including a transmission loss from a pass band having a bandwidth from 5.855 GHz to 5.925 GHz. Resonators include a support member with a multilayer reflector structure; a first electrode including tungsten; a piezoelectric film including aluminum scandium nitride; a second electrode including tungsten; and a passivation layer including silicon nitride. At least one resonator includes at least a portion of the first electrode located within a cavity region defined by a surface of the support member.

An acoustic resonator filter includes: a series unit including at least one series acoustic resonator electrically connected, in series, between first and second ports configured to pass a radio frequency (RF) signal; a first shunt unit disposed on a first shunt connection path between the at least one series acoustic resonator and a ground, the first shunt unit including a plurality of shunt acoustic resonators connected to each other in series and having different resonance frequencies; and a second shunt unit disposed in a second shunt connection path between the at least one series acoustic resonator and the ground, the second shunt unit including at least one shunt acoustic resonator and having higher inductance than inductance of the first shunt unit.

A bulk acoustic wave resonator includes a substrate, a first electrode and a second electrode formed on the substrate, and a piezoelectric layer provided between the first electrode and the second electrode. Either one or both of the first electrode and the second electrode include a molybdenum-tungsten alloy having a weight ratio of molybdenum to tungsten in a range of 3:1 to 1:3.

A filter includes: one or more series resonators connected in series between an input terminal and an output terminal, the one or more series resonators including a series resonator located closest to the output terminal, the series resonator located closest to the output terminal having a resonant frequency that is 99.6% or less of or 102.2% or greater of a center frequency of a passband; one or more parallel resonators connected in parallel between the input terminal and the output terminal; and an inductor connected in parallel to the series resonator located closest to the output terminal.

A packaged acoustic wave component includes a support substrate, a multi-layer piezoelectric substrate disposed over a first side of the support substrate, one or more metal layers disposed on a second side of the support substrate that is opposite the first side of the support substrate, and one or more surface acoustic wave resonators or filters disposed over the multi-layer piezoelectric substrate. The one or more surface acoustic wave resonators or filters include a multi-mode surface acoustic wave resonator or filter (e.g., dual mode surface acoustic wave resonator or filter). One or more vias extend through the support substrate and electrically connect the multi-mode surface acoustic wave resonator or filter and the one or more metal layers to provide a ground connection for the multi-mode surface acoustic wave resonator or filter, while reducing parasitic inductance.

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.