A new design methodology for electro-mechanical Sigma- Delta-Modulators

Sigma-Delta-Modulators (SDM) are the most successful technique for analog-to-digital (A/D) conversion, especially for high resolution applications. Similar techniques and architectures have been applied to micro-electro-mechanical systems (MEMS) by incorporating a micromachined sensing element in a SDM force-feedback loop. However, compared to the design of purely electrical SDM there are important differences due to the integration of the sensing element regarding stability and performance. As a result, there are very few systematic methods for the design of electro-mechanical SDM compared to purely electrical SDM. In this paper, a new systematic design methodology is proposed to realize an electro-mechanical SDM system which is demonstrated at system level for a bulk micromachined, capacitive accelerometer.