A High-Performance Fourth-Order Sigma-Delta Micromachined Accelerometer
This paper reports on a system level design and analysis of a single-loop fourth-order sigma-delta (ΣΔ) accelerometer. Compared with a second-order single-loop ΣΔ modulator (ΣΔM) formed by the sensing element here the sensing element is cascaded with two extra electronic integrators to form the fourth ΣΔM, which has the advantages of better signal to quantization noise ratio (SQNR). System level simulation results indicate that the SQNR is 96.86 dB, and the effective number of bits (ENOB) is 15.8 bits when the over sampling ratio (OSR) is 128. Stability of the system is analyzed by root locus method based on the linear model established in this work, and the minimum gain of the quantizer Kq min is about 0.375.
Y. G. Li et al., "A High-Performance Fourth-Order Sigma-Delta Micromachined Accelerometer", Key Engineering Materials, Vol. 483, pp. 422-426, 2011