Higher Order Sigma-Delta Modulator Interfaces for MEMS Capacitive Sensors

摘要

We have investigated various higher order SDM topologies to be used with a micromachined sensing element of a standard capacitive accelerometer. Achieving stability is a challenging task since it is not possible to feed back a signal to the internal node of the sensing element. Stability can be investigated by simulations using Matlab and Simulink. The noise shaping characteristic can been greatly improved compared to an architecture where the sensing element is used as a loop filter only. The approach presented in this paper can be easily adapted for other capacitive micromachined sensors.