Elimination of nonlinearity in sigma delta MEMS accelerometer

This paper presents a method of eliminating nonlinearity in sigma delta MEMS accelerometer by keeping the proof mass fixed at the geometrically symmetrical position (the zero position). Published architectures on sigma delta MEMS accelerometer fail to maintain the proof mass at the zero position with nonzero static input. The output voltage is nonlinear to the input because of the displacement The proposed accelerometer system consists of sense element fabricated in SOG process and ASIC in 2P4M 0.35μm CHART CMOS process. Circuit implementations in ASIC generate excitation signal to sense the input acceleration and feedback signal to form electrostatic feedback force. Time division multiplexing is applied so that excitation and feedback signal can work simultaneously on the three plates sense element Both simulations with SIMULINK and test results show that the proof mass is maintained at the zero position with different static input within the range. A nonlinearity of 0.065%, 10μg noise floor and an input range of about ±3g are achieved.