Abstract: Aspects of the disclosure relate to piezoelectric microelectromechanical systems (MEMS) devices. A piezoelectric MEMS device may include a transducer body including an acoustic cavity extending from a bottom surface to a top surface; and a substrate including a plurality of layers and coupled to the bottom surface of the transducer body, the substrate including a hole formed by the plurality of layers, and wherein the plurality of layers comprises a solder mask, a top metal layer, and a plurality of tapered layers below the top metal layer having incrementally varying aperture sizes relative to at least one adjacent layer.

Abstract: Disclosed are techniques for acoustic limiters for micro-electrical-mechanical systems (MEMS) microphones and other devices. In an aspect, an acoustic limiter comprises a first housing and a second housing separated by a flexible membrane. The membrane has at least one opening to allow air to flow between the housings. The membrane flexes in response to acoustic pressure within the first housing. If the acoustic pressure is above a threshold value, the membrane flexes a distance into the second housing such that the rigid structure completely or partially blocks the one or more openings through the membrane, which limits airflow speed into the second housing, thus limiting the acoustic pressure within the second housing. In an aspect, the acoustic limiter protects a MEMS microphone element mounted to the second housing, the first housing being the microphone input.

Abstract: An apparatus is disclosed for implementing a surface-acoustic-wave (SAW) filter with dielectric material disposed in a piezoelectric layer. In an example aspect, the apparatus includes a surface-acoustic-wave filter with a piezoelectric layer, an electrode structure, and dielectric material. The piezoelectric layer has at least one channel. The dielectric material is disposed in the at least one channel of the piezoelectric layer and is at least partially covered by the electrode structure.

Abstract: An apparatus is disclosed for implementing a surface-acoustic-wave (SAW) filter with dielectric material disposed in a piezoelectric layer. In an example aspect, the apparatus includes a surface-acoustic-wave filter with a piezoelectric layer, an electrode structure, and dielectric material. The piezoelectric layer has at least one channel. The dielectric material is disposed in the at least one channel of the piezoelectric layer and is at least partially covered by the electrode structure.