Analysis and compensation for nonlinearity of sandwich MEMS capacitive accelerometer induced by fabrication process error

Abstract The effect of fabrication process error on the nonlinearity of sandwich MEMS capacitive accelerometer is analyzed in the paper. Firstly, after the packaging of the accelerometer, the displacement offset and torsion angle of the sensitive proof mass are obtained by CV testing. The gravitational field rolling four-position testing method is used to calibrate the bias, the scale factor, and the second-order nonlinearity coefficient of the accelerometer under different compensation capacitance. Testing results show that the second-order nonlinearity coefficient has a linear relationship with the compensation capacitance. A physical model of the accelerometer is built to analyze the effect of fabrication process error on the nonlinearity of the accelerometer, justifying the experimental linear relationship. Using the relationship, the capacitance compensation method is optimized, thus improving the efficiency of compensation. In the optimal case, the second-order nonlinearity coefficient of the accelerometer can be reduced to the order of 10−4 only by three capacitance compensations.