High-order electromechanical ΣΔ modulation in micromachined inertial sensors

Analysis of second-order electromechanical sigma-delta (ΣΔ) inertial sensors shows that in-band quantization error introduces a resolution penalty, which cannot be eliminated by oversampling. In addition, a tradeoff between resolution and phase compensation forces such systems to operate with reduced phase margin. This paper introduces high-order electromechanical ΣΔ modulation as an approach, which eliminates the quantization noise overhead and allows for increased phase compensation without degrading the resolution. Quasi-linear analysis is used to evaluate the contribution of the individual noise sources to the output of the system and to examine the effect of noise interaction on the behavior of electromechanical ΣΔ modulators.