Resolution Enhancement of a Sigma-Delta Micro-Accelerometer Using Signal Prediction

This paper presents a new design of a closed-loop sigma-delta accelerometer using an acceleration prediction feedback element. Thanks to a Kalman state estimator associated with a Linear-Quadratic-Gaussian (LQG) controller, the proof mass is maintained near its position of equilibrium. Consequently, operating on the relatively small proof mass displacement makes it possible to enhance the performance of the sigma-delta converter. This architecture shows an increase of more than 20 dB in signal quantization noise ratio compared to conventional sigma-delta accelerometers and has the advantage of being a completely digital solution.