An acoustic wave device includes a support substrate, an acoustic reflection film on the support substrate, a piezoelectric layer on the acoustic reflection film, the piezoelectric layer including first and second primary surfaces, and first and second flat-plate electrodes on the first and second primary surfaces of the piezoelectric layer. The acoustic reflection film includes high acoustic impedance layers and low acoustic impedance layers alternately stacked together. At least one layer of the high acoustic impedance and low acoustic impedance layers is a stack of layers of first and second materials having equal or substantially equal acoustic impedances for at least one of longitudinal acoustic impedance and transversal acoustic impedance. The interface between the layers of first and second materials has irregularities.

An acoustic wave device includes an acoustic wave filter configured to filter a radio frequency signal and a loop circuit coupled to the acoustic wave filter. The loop circuit is configured to generate an anti-phase signal to a target signal at a particular frequency. The loop circuit includes a Lamb wave resonator having a piezoelectric layer and an interdigital transducer electrode disposed on the piezoelectric layer. The piezoelectric layer includes free edges. An edge of the piezoelectric layer is configured to one of suppress or scatter reflections of acoustic waves generated by the interdigital transducer electrode from the edge of the piezoelectric layer.

Techniques for improving Bulk Acoustic Wave (BAW) resonator structures are disclosed, including fluidic systems, oscillators and systems that may include such devices. A bulk acoustic wave (BAW) resonator may comprise a substrate and a first layer of piezoelectric material. The bulk acoustic wave (BAW) resonator may comprise a top electrode. A sensing region may be acoustically coupled with the top electrode of the bulk acoustic wave (BAW) resonator.

It is proposed to enhance the bandwidth of a SMR BAW resonator (TE,PL,BE) by circuiting it with a planar coil (WG1, WG2) that is realized in a high impedance layer (HI) of the Bragg mirror (BM) or in an additional metal layer below the Bragg mirror.

An acoustic wave device includes an acoustic wave filter configured to filter a radio frequency signal and a loop circuit coupled to the acoustic wave filter. The loop circuit is configured to generate an anti-phase signal to a target signal at a particular frequency. The loop circuit includes a Lamb wave resonator having a piezoelectric layer and an interdigital transducer electrode disposed on the piezoelectric layer. The piezoelectric layer includes free edges. An edge of the piezoelectric layer is configured to one of suppress or scatter reflections of acoustic waves generated by the interdigital transducer electrode from the edge of the piezoelectric layer.

A resonator element for use in a filter is provided. The resonator element includes a first resonator acoustically coupled to a second or third resonator or both. The first resonator has terminals for incorporation in a filter structure. A tuning circuit is coupled to the second or third resonator or both to enable tuning of the resonator element. The tuning circuit includes a variable capacitor and an inductor.

A laterally excited bulk acoustic wave device is disclosed. The laterally excited bulk acoustic wave device can include a support substrate, a solid acoustic mirror on the support substrate, a piezoelectric layer on the solid acoustic mirror, and an interdigital transducer electrode on the piezoelectric layer. The interdigital transducer electrode is arranged to laterally excite a bulk acoustic wave.

Techniques are disclosed for forming integrated circuit single-flipped resonator devices that include an electrode formed of a two-dimensional electron gas (2DEG). The disclosed resonator devices may be implemented with various group III-nitride (III-N) materials, and in some cases, the 2DEG may be formed at a heterojunction of two epitaxial layers each formed of III-N materials, such as a gallium nitride (GaN) layer and an aluminum nitride (AlN) layer. The 2DEG electrode may be able to achieve similar or increased carrier transport as compared to a resonator device having an electrode formed of metal. Additionally, in some embodiments where AlN is used as the piezoelectric material for the resonator device, the AlN may be epitaxially grown which may provide increased performance as compared to piezoelectric material that is deposited by traditional sputtering techniques.

In accordance with an embodiment, an RF system includes a transmit path having a transmit RF filter and an adjustable transmit phase shifter/matching network coupled between the transmit RF filter and a transmit antenna port, where the adjustable transmit phase shifter/matching network is configured to transform an impedance of the transmit RF filter at a receive frequency from a first lower impedance to a first higher impedance at the transmit antenna port; and a receive path having a receive RF filter and an adjustable receive phase shifter/matching network coupled between the receive RF filter and a receive antenna port, where the adjustable receive phase shifter/matching network is configured to transform an impedance of the receive RF filter at a transmit frequency from a second lower impedance to a second higher impedance at the receive antenna port.

A notch filter includes an inductor coupled between an input node and an output node, and a dual-resonator structure coupled between the input node, the output node, and ground.