An acoustic device includes a foundation structure and a transducer provided over the foundation structure. The foundation structure includes a piezoelectric layer between a top electrode and a bottom electrode. The piezoelectric layer has an active portion within an active region of the transducer, and a bi-polar border portion within a border region of the transducer. The piezoelectric material in the active portion has a first polarization. The bi-polar border portion has a first sub-portion and a second sub-portion, which resides either above or below the first sub-portion. The piezoelectric material in the first sub-portion has the first polarization, and the piezoelectric material in the second sub-portion has a second polarization, which is opposite the first polarization.

Aspects of this disclosure relate to an acoustic wave device that includes a bulk acoustic wave resonator and a Lamb wave element implemented on a common substrate. In some instances, the bulk acoustic wave resonator can be a film bulk acoustic wave resonator. Related radio frequency modules and wireless communication devices are disclosed.

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.

Multiplexers are disclosed. A multiplexer can include a first filter and a second filter that are coupled to a common node. The second filter can include a first type of acoustic wave resonators (e.g., bulk acoustic wave resonators) and a series acoustic wave resonator of a second type (e.g., a surface acoustic wave resonator) that is coupled between the acoustic wave resonators of the first type and the common node. The first filter can provide a single-ended radio frequency signal. In certain embodiments, the first filter can be a receive filter and the second filter can be a transmit filter.

Disclosed is a radio frequency (RF) filter that vertically integrates an acoustic wave filter with an integrated passive device (IPD) filter. The acoustic wave filter provides selectivity at fundamental frequency band while the IPD filter provides rejection at harmonic frequency bands.

A method of making an acoustic wave sensor includes the steps of providing a piezoelectric substrate layer and printing on the substrate layer a sensor layer comprising a first interdigitated acoustic wave transducer, a sensing film, and positioned on an opposing side of the sensing film from the first interdigitated acoustic wave transducer at least one selected from the group consisting of a second interdigitated acoustic wave transducer and a Bragg reflector. An insulation layer can be printed. An antenna can be printed in an antenna layer, and the insulation layer can be interposed between the antenna layer and the sensor layer. An electrical connection can be printed between the antenna and the first interdigitated acoustic wave transducer. An acoustic wave sensor is also disclosed.

A BAW resonator filter can include a BAW resonator pass-band filter ladder, the BAW resonator pass-band filter ladder can be configured to pass frequency components of an input signal in a pass-band of frequencies received at an input node of the BAW resonator pass-band filter ladder to an output node of the BAW resonator pass-band filter ladder. A first rejection-band series resonator can be coupled in series between an input port of the BAW resonator pass-band filter ladder and the input node, the first rejection-band series resonator can have a first anti-resonant frequency peak in a rejection-band of frequencies that is less than the pass-band of frequencies. A second rejection-band series resonator can be coupled in series between an output port of the BAW resonator filter and the output node, the second rejection-band series resonator can have a second anti-resonant frequency peak in the rejection-band of frequencies.

Devices and systems useful in concurrently receiving and transmitting Wi-Fi signals and Bluetooth signals in the same frequency band are provided. By way of example, an electronic device includes a transceiver configured to transmit data and to receive data over channels of a first wireless network and a second wireless network concurrently. The transceiver includes a plurality of filters configured to allow the transceiver to transmit the data and to receive the data in the same frequency band by reducing interference between signals of the first wireless network and the second wireless network.

Aspects of this disclosure relate to a parallel hybrid acoustic passive filter. The parallel hybrid acoustic passive filter includes a first sub-filter and a second sub-filter. The first sub-filter includes a first acoustic resonator and a first non-acoustic passive component. The second sub-filter includes a second acoustic resonator and second first non-acoustic passive component. The first sub-filter and the second sub-filter are together arranged to filter a radio frequency signal. The parallel hybrid acoustic filter can be a band pass filter or a band stop filter, for example. Related multiplexers, wireless communication devices, and methods are disclosed.

An acoustic wave device includes a piezoelectric substrate including a crystal axis and an IDT electrode. When an acoustic wave propagation direction is a first direction and a direction perpendicular to the first direction is a second direction, the crystal axis of the piezoelectric substrate is inclined toward the second direction with respect to the thickness direction. The IDT electrode includes first and second electrode fingers interdigitated with each other. The portion where the first and second electrode fingers overlap in the first direction is a crossing region. The crossing region includes a center region that is centrally located in the second direction and first and second low-acoustic-velocity regions that are located on both sides of the center region in the second direction and in which the acoustic velocity is lower than the acoustic velocity in the center region. The first and second low-acoustic-velocity regions are asymmetrical.