Abstract: An apparatus is disclosed for implementing a microacoustic filter with a cavity stack. In an example aspect, the apparatus includes a microacoustic filter with an electrode structure, a cavity stack, a buffer layer, and a piezoelectric layer. The cavity stack comprises a conductive layer, a substrate layer, and at least two pillars extending past a plane defined by a surface of the substrate layer and towards the conductive layer to form a cavity between the substrate layer and the conductive layer. The buffer layer is disposed between the conductive layer of the cavity stack and the electrode structure. The piezoelectric layer is disposed between the buffer layer and the electrode structure.

Abstract: An apparatus is disclosed for partially suspending a piezoelectric layer using a dielectric. In an example aspect, the apparatus includes a microacoustic filter with a substrate layer, a piezoelectric layer, an electrode structure that is in contact with the piezoelectric layer, and a dielectric. The electrode structure includes multiple fingers arranged across a plane having a first axis that is perpendicular to the multiple fingers and a second axis that is parallel to the multiple fingers. The dielectric is configured to separate the piezoelectric layer from the substrate layer and define a cavity between the piezoelectric layer and the substrate layer. The dielectric is also configured to support the piezoelectric layer across at least three points along the first axis.

Abstract: An apparatus is disclosed for suspending an electrode structure using a dielectric. In an example aspect, the apparatus includes a surface-acoustic-wave filter with a piezoelectric layer and an electrode structure. The electrode structure has a first surface facing the piezoelectric layer and separated from the piezoelectric layer by a distance. The surface-acoustic-wave filter also includes a dielectric disposed on at least one other surface of the electrode structure and configured to extend past a plane defined by the first surface of the electrode structure and toward the piezoelectric layer to define a cavity between at least a portion of the first surface of the electrode structure and the piezoelectric layer.

Abstract: An apparatus is disclosed for a surface-acoustic-wave filter with a compensation layer having multiple densities. In an example aspect, the apparatus includes at least one surface-acoustic-wave filter with a piezoelectric layer, a substrate layer, and a compensation layer positioned between the piezoelectric layer and the substrate layer. The compensation layer includes a first portion having a first density and a second portion having a second density. The second density is greater than the first density. The first portion is positioned closer to the piezoelectric layer as compared to the second portion. The second portion is positioned closer to the substrate layer as compared to the first portion.