Simulation of Micromachined Inertial Sensors with Higher-Order Single Loop Sigma-Delta Modulators

摘要

Micromachined capacitive inertial sensors incorporated in sigma-delta force-feedback loops have been proven to improve linearity, dynamic range and bandwidth, and also provide a direct digital output. Previous work mainly focused on using only the sensing element to form a 2nd-order single loop sigma-delta modulator (ΣΔM ). Therefore, the advantages of higher-order (4th-order and 5th-order) single loop electro-mechanical ΣΔM have not been explored, especially for inertial sensors that require higher Signal to Quantization Noise Ratio (SQNR), wide-band signal and low power dissipation. This paper presents architecture for higher-order single loop electro-mechanical ΣΔM with optimal stable coefficients that lead to better SQNR. Simulations show the maximum SQNR of 3rd-order, 4th-order and 5th-order ΣΔM is 88dB, 105dB and 122dB, respectively, using an Oversampling Ratio (OSR) of 256.