A single-axis and three-electrode MEMS accelerometer with linear output and zero-stiffness

Abstract This paper presents a high-performance MEMS accelerometer that utilizes a single set of multi-functional gap-varying double-sided parallel plate (DSPP) capacitors. We propose a self-centering method for the geometric center of the DSPP. The self-centering method enables a linear relationship between the force-to-rebalance (FTR) output and the applied acceleration, effectively addressing the inherent nonlinearity issue of three-electrode accelerometers. Within the range of −1 g to 1 g ( g = 9.8 m s −2 ), the accelerometer achieves a nonlinear error of 106 ppm. A novel FTR control method based on three-electrode configuration and Pythagorean identity is proposed to realize a reduced constant-stiffness and high-linearity FTR. It enables a high-degree integration of displacement detection, FTR, stiffness tuning, and position calibration on a simple three-electrode DSPP structure. Experimental results demonstrate the effectiveness of self-centering and constant quasi-zero stiffness control, resulting in a bias instability of about 0.57 μ g and a noise floor of 0.85 μ g/√Hz for the proposed accelerometers. In comparison to the conventional accelerometer with multiple capacitors, the proposed accelerometer achieves a full-scale range twice as wide as the first (up to ±4.22 g) and about 50% reduction of layout area of capacitors with little accuracy degradation.