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 wave filter includes a first chip and a second chip electrically connected to the first chip. Each of the chips includes a support substrate, a plurality of acoustic films, a piezoelectric film, and an excitation electrode sequentially stacked on one another. The plurality of acoustic films are sequentially stacked on the support substrate and materials for acoustic films stacked on each other are different from each other.

Provided are a band-stop filter and a multi-frequency band-stop filter. The band-stop filter includes at least one band-stop filtering unit; the at least one band-stop filtering unit includes an input port, an output port, at least two resonators, and at least one inductive element; and the first terminal of the first resonator is connected between the input port and the inductive element, and the first terminal of the second resonator is connected between the output port and the inductive element.

A filter device includes a filter circuit including series-arm resonators and series-arm-resonator connecting wires, and an additional circuit including a resonator including first and second interdigital transducer electrodes, first and second capacitors connected between the first and second interdigital transducer electrodes and the filter circuit, and first and second I-C connecting wires connected to the first and second interdigital transducer electrodes and the first and second capacitors, the additional circuit being connected in parallel with a portion of the series-arm resonators in the filter circuit. The first and second interdigital transducer electrodes are output-side interdigital transducer electrodes. A capacitance of the first capacitor is smaller than the capacitance of the second capacitor. A shortest distance among distances between the first I-C connecting wire and the series-arm-resonator connecting wires is shortest among shortest distances between the I-C connecting wires and the series-arm-resonator connecting wires.

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.

Filter characteristics of a first filter are improved while suppressing degradation in filter characteristics of a second filter. A multiplexer includes a first terminal, a second terminal, a first filter, a second filter, and a capacitive element. The first filter and the second filter are connected to an antenna via the first terminal. The first filter includes a plurality of series arm resonators, a plurality of parallel arm resonators, and an inductor. The inductor is provided between the parallel arm resonator and ground. A first end portion of the capacitive element is connected to a first path at a position in between the series arm resonator that is the closest to the first terminal and the second terminal. A second end portion of the capacitive element is connected between the parallel arm resonator and the inductor.

Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

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.

A filter (22A) includes: a series arm circuit (11) that is connected between an input/output terminal (22m) and an input/output terminal (22n); and a parallel arm circuit (12) that is connected between a node (x1), which is on a path that connects the input/output terminal (22m) and the input/output terminal (22n), and ground. The parallel arm circuit (12) includes a parallel arm resonator (22p) and an impedance circuit (13) that is serially connected to the parallel arm resonator (22p). The impedance circuit (13) includes a first impedance element, which is one of an inductor and a capacitor, a second impedance element, which is the other of an inductor and a capacitor, and a switch (22SW) that is serially connected to the second impedance element. A first series circuit (14) comprising of the second impedance element and the switch (22SW) is connected in parallel with the first impedance element.

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.