CMOs interface circuitry for a closed-loop capacitive MEMS accelerometer

CMOS interface circuitry for closed-loop capacitive MEMS accelerometer is presented in this paper. The switched-capacitor (SC) charge integration method is used for the capacitive sensing, correlated double sampling (CDS) technique is introduced to compensate the finite gain of operation amplifiers, reduce 1/f noise and offsets. In order to enhance stability of system and the frequency response performance, proportional-integral-differential (PID) adjuster are applied. An elaborate layout design with 0.5 um CMOS process was completed and nonidealities are analyzed and optimized. The post-simulation results indicate that the sensitivity of the system is 1.22 V/g, the full measurement range is -3g to +3g, the minimum acceleration detected can be achieved 30 ug, nonlinearity is less than 0.16%.