Multiplexing circuits with bulk acoustic wave (BAW) resonators as network elements for higher performance are provided. Multiplexing networks which support newer fourth generation (4G) and fifth generation (5G) standards may include a combination of multiplexers having a number of radio frequency (RF) filters connected to an antenna at the same time. One critical aspect of such a multiplexer design is the loading of these filters to each other, in which the static capacitance presented by a filter can be beneficial or detrimental to other filters in the multiplexing network. Aspects of the present disclosure introduce a BAW resonator to improve multiplexing network performance using the frequency-dependent capacitance, resonance, and/or anti-resonance of the BAW resonator.

An acoustic wave filter device includes a second filter section connected to a first filter section. The second filter section includes acoustic wave resonators in a ladder circuit configuration. Of the acoustic wave resonators in the first and second filter sections, the acoustic wave resonator having the smallest fractional bandwidth is included in the second filter section. In the second filter section, inductors are respectively connected between parallel arm resonators and a reference potential. Attenuation near a pass band in the second filter section is larger than attenuation near a pass band in the first filter section.

Interdigital transducer (IDT) and reflective structure arrangements for surface acoustic wave (SAW) devices are disclosed. Representative SAW devices are described herein with reduced overall size while maintaining good quality factors. In certain embodiments, a SAW device may include an IDT arranged between reflective structures on a piezoelectric material. The reflective structures may include reflective IDTs that are configured to have a phase difference with the IDT to reflect and confine acoustic waves in the piezoelectric material. In certain embodiments, the reflective structures may be electrically connected to at least one of an input signal or an output signal. In this manner, the reflective structures may be configured with reduced size as compared to conventional reflective structures such as gratings, thereby providing a SAW device with reduced dimensions without a negative impact on device performance.

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.

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.

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.

The invention provides a filter device, an RF front-end device and a wireless communication device. The filter device comprises a substrate, at least one resonance device, a passive device and a connector, wherein the at least one resonance device has a first side and a second side opposite to the first side, the substrate is located on the first side, and the passive device is located on the second side. The at least one resonance device is connected to the passive device through the connector. The RF filter device formed by integrating the resonance device (such as an SAW resonance device or a BAW resonance device) and the passive device (such as an IPD) in one die can broaden the passband width, has a high out-of-band rejection, and occupies less space in an RF front-end chip.

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.