Design of a poly silicon MEMS microphone for high signal-to-noise ratio

Abstract

This paper reports on the state of the art silicon micromachined microphone utilizing a dual poly silicon membrane system. MEMS chips from 1.4mm down to 1.0mm side length are applied for mobile communication. Design aspects related with key performance parameters such as sensitivity, signal to noise ration and distortion are discussed. Sensitivity of - 38BV/Pa is achieved for different microphone membrane diameters. A maximum signal to noise ration of 66dB(A) for the largest system could be achieved. The perfect fit of simulation versus measurements enables deeper analysis and balancing of noise contributors. Environmental noise suppression of 5dB by acoustical high pass design is demonstrated.