Dynamics-level Design for Discrete- and Continuous-Time Band-pass Sigma-Delta-Modulators for Micro-machined Accelerometers

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Description/Abstract

High-performance micro-electro-mechanical systems (MEMS) sensors can be implemented by incorporating a micro-machined capacitive sensing element in a Sigma-Delta-Modulators force-feedback loop, forming an electro-mechanical Sigma-Delta Modulator (EM-SDM). We propose a transfer-function based design methodology to realize discrete- and continuous-time low-pass EM-SDM. The design is performed at the level of the integrated system consisting of the electro-mechanical sensor and of the electronic circuit; we call this the dynamics-level. We also illustrate a technique to perform the conversion of the discrete-time design to a continuous-time one. The approach is demonstrated through an EM-SDM design example for a bulk micro-machined, capacitive accelerometer.