Abstract: An acoustic wave filter includes a piezoelectric layer. A first acoustic wave device includes a portion of the piezoelectric layer and a first multi-layer interdigital transducer electrode disposed over the first portion of the piezoelectric layer. Additional acoustic wave devices are coupled to the first acoustic wave device, the additional acoustic wave devices including a second portion of the piezoelectric layer and a plurality of multi-layer interdigital transducer electrodes disposed over the second portion of the piezoelectric layer. At least one of the plurality of multi-layer interdigital transducer electrodes includes a layer that is thinner than a corresponding layer of the same material of the first multi-layer interdigital transducer electrode of the first acoustic wave device.

Abstract: Aspects and embodiments disclosed herein include a bulk acoustic wave resonator comprising a layer of piezoelectric material and one of a top electrode disposed on top of the layer of piezoelectric material or a bottom electrode disposed on a bottom of the layer of piezoelectric material, the one of the top electrode or the bottom electrode including a Bragg pair having alternating layers of a first metal and a second metal.

Abstract: Aspects of this disclosure relate to a bulk acoustic wave device with a multi-gradient raised frame. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a multi-gradient raised frame structure. The multi-gradient raised frame structure includes a first raised frame layer and a second raised frame layer. The second raised frame layer extends beyond the first raised frame layer. The second raised frame layer is tapered on opposing sides.

Abstract: Methods related to gradient raised frames in film bulk acoustic resonators. According to certain aspects, a method for fabricating a film bulk acoustic resonator device can include: forming a first metal layer over a substrate; forming a piezoelectric layer; forming a second metal layer, the piezoelectric layer positioned between the first and second metal layers; and forming a gradient raised frame implemented relative to one of the first and second metal layers and configured to improve reflection of lateral mode waves and to reduce conversion of main mode waves into lateral mode waves.

Abstract: An acoustic wave device includes a piezoelectric layer and an interdigital transducer electrode disposed over the piezoelectric layer. The interdigital transducer electrode is thicker in a center region of the interdigital transducer electrode than in a gap region of the interdigital transducer electrode to thereby reduce a mass loading of the interdigital transducer electrode in the gap region. The interdigital transducer electrode has a layer of less dense material disposed of a layer of more dense material.

Abstract: Aspects of this disclosure relate to a bulk acoustic wave device with a multi-gradient raised frame. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a multi-gradient raised frame structure configured to cause lateral energy leakage from a main acoustically active region of the bulk acoustic wave device to be reduced. The multi-gradient raised frame structure is tapered on opposing sides.

Abstract: Aspects of this disclosure relate to a bulk acoustic wave device with a multi-gradient raised frame. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a multi-gradient raised frame structure. The multi-gradient raised frame structure includes a first raised frame layer and a second raised frame layer. The second raised frame layer extends beyond the first raised frame layer. The second raised frame layer is tapered on opposing sides.

Abstract: A bulk acoustic resonator comprises a membrane including a piezoelectric film having multiple layers of piezoelectric material. At least one of the multiple layers of piezoelectric material has a different dopant concentration than another of the multiple layers of piezoelectric material.

Abstract: A bulk acoustic wave resonator configured as a capacitor has a piezoelectric structure including a mesa region suspended above a substrate to define a cavity. The piezoelectric structure includes a perimeter region surrounding a perimeter of the mesa region with a sloping portion that gradually slopes towards the substrate and a connecting portion proximate the substrate that supports the piezoelectric structure with respect to the substrate. The piezoelectric structure incudes a bottom electrode layer, a top electrode layer, and a piezoelectric layer therebetween. An overlapping region where the bottom electrode layer and the top electrode layer overlap extends across at least a width of the mesa region between opposing sides of the perimeter region.

Abstract: Methods related to gradient raised frames in film bulk acoustic resonators. According to certain aspects, a method for fabricating a film bulk acoustic resonator device can include: forming a first metal layer over a substrate; forming a piezoelectric layer; forming a second metal layer, the piezoelectric layer positioned between the first and second metal layers; and forming a gradient raised frame implemented relative to one of the first and second metal layers and configured to improve reflection of lateral mode waves and to reduce conversion of main mode waves into lateral mode waves.

Abstract: A rain detection device for sensing rain drops on a surface includes at least one sensor unit and at least one evaluation unit. The sensor unit includes at least one capacitive sensor element. The sensor element is configured such that a capacitance characteristic of the sensor element changes based on an object contacting the surface. The evaluation unit is configured to detect rain drops on the surface based on a differential signal of the sensor element. The evaluation unit is configured to detect a rain drop on the surface based on a symmetry characteristic of the differential signal with respect to a zero point.

Abstract: A surface acoustic wave device is disclosed. The surface acoustic wave device can include a single crystal support layer, an intermediate single crystal layer positioned over the single crystal support layer, a lithium based piezoelectric layer positioned over the intermediate single crystal layer, and an interdigital transducer electrode positioned over the lithium based piezoelectric layer, the surface acoustic wave device configured to generate a surface acoustic wave. The single crystal layer can be a quartz layer, such as a z-propagation quartz layer. A thermal conductivity of the single crystal support layer is greater than a thermal conductivity of the intermediate single crystal layer, and the thermal conductivity of the single crystal support layer is greater than a thermal conductivity of the lithium based piezoelectric layer.

Abstract: Aspects of this disclosure relate to a bulk acoustic wave device with a multi-layer raised frame. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a multi-layer raised frame structure configured to cause lateral energy leakage from a main acoustically active region of the bulk acoustic wave device to be reduced. The multi-layer raised frame structure includes a first raised frame layer embedded in the piezoelectric layer and a second raised frame layer. The first raised frame layer has a lower acoustic impedance than the piezoelectric layer.

Abstract: The present specification relates generally to unmanned aerial vehicles, and specifically to a vertical take-off and lift unmanned aerial vehicle configured for high speed, long-distance flight, and vertical take-off and lift, while carrying a significant payload. The aerial vehicle includes a first propeller and a second propeller, each comprising at least two blades and each disposed on opposite lateral edges of the aerial vehicle; a tail segment forming a trailing edge of the aerial vehicle, wherein the tail segment comprises: an elevator; and a first wing and a second wing, each comprising an aileron. The aerial vehicle further includes four fins, wherein the four fins are affixed to lateral edges behind the first propeller or the second propeller and configured as endplates; a motor; and a power supply.

Abstract: Disclosed herein is a bulk acoustic wave filter comprising a number of acoustic wave resonators, each acoustic wave resonator being encompassed by a polygon including vertices of a mesh optimized to provide a reduced filter size of the bulk acoustic wave filter integrated on a die.

Abstract: A surface acoustic wave device has a trench formed adjacent to at least one interdigital transducer electrode into the piezoelectric substrate. The trench can be adapted to enhance confinement of acoustic wave energy provided by the interdigital transducer electrode.

Abstract: Aspects and embodiments disclosed herein include an acoustic wave device comprising a substrate, a pair of inter-digital transducer (IDT) electrodes formed on the substrate, each of the pair of IDT electrodes including a bus bar and a plurality of fingers extending from the bus bar, fingers of one IDT electrode arranged interleaved with fingers of the other IDT electrode, each of the bus bars of the pair of IDT electrodes having a slotted portion configured on an upper surface of the bus bars opposite to a lower surface contacting the substrate such that at least one hollow within each of the bus bars is opened at least at the upper surface of each of the bus bars, and a dielectric film covering the pair of IDT electrodes, at least a portion of the dielectric film filling in the at least one hollow of each of the bus bars.

Abstract: An acoustic wave device is disclosed. The acoustic wave device can include a piezoelectric layer, and an interdigital transducer electrode formed with the piezoelectric layer. The interdigital transducer electrode includes a first layer, a second layer over the first layer, and a seed layer between the first layer and the piezoelectric layer. A combination of the first layer and the seed layer has a resistivity that is lower than a resistivity of the first layer alone.

Abstract: Aspects of this disclosure relate to a surface acoustic wave filter with an acoustic velocity adjustment structure. The surface acoustic wave filter can include a first interdigital transducer electrode disposed on a piezoelectric layer, an acoustic reflector disposed on the piezoelectric layer, and a second interdigital transducer electrode disposed on the piezoelectric layer. The second interdigital transducer electrode is longitudinally coupled to the first interdigital transducer electrode and positioned between the first interdigital transducer electrode and the acoustic reflector. The acoustic velocity adjustment structure can be positioned over at least a gap between the first interdigital transducer electrode and the second interdigital transducer electrode.

Abstract: Gradient raised frames in film bulk acoustic resonators. In some embodiments, a film bulk acoustic resonator device can include a substrate, first and second metal layers implemented over the substrate, a piezoelectric layer between the first and second metal layers, and a gradient raised frame implemented relative to one of the first and second metal layers and configured to improve reflection of lateral mode waves and to reduce conversion of main mode waves into lateral mode waves.