A high-performance accelerometer with a fifth-order sigma-delta modulator

Dong, Yufeng, Kraft, Michael, Gollasch, Carsten and Redman-White, William (2005) A high-performance accelerometer with a fifth-order sigma-delta modulator. Journal of Micromechanics and Microengineering, 15 (7), S22-S29. (doi:10.1088/0960-1317/15/7/004).

Abstract

To verify the effectiveness of a higher order electromechanical sigma–delta modulator (ΣΔM), a micromachined accelerometer is fabricated. The in-plane sensor with fully differential structure has a mechanical noise floor below 1 µg Hz^-1/2, static sensitivity 16 pF g^-1 and resonant frequency 325 Hz. FEM analyses are performed to verify these key parameters. The silicon-on-glass sensor is fabricated by deep reactive ion etching (DRIE) and anodic bonding. Compared with a second-order electromechanical ΣΔM, which only uses the sensing element as a loop filter, here it is cascaded with additional electronic integrators to form a fifth-order electromechanical ΣΔM, which leads to better signal to quantization noise ratio (SQNR). This novel approach is analysed and system level simulations are presented. A printed circuit board (PCB) prototype of this high-order ΣΔM loop was built and tested. The experimental data agree well with the simulation results.

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