Wang Xuefeng, Zhang Penghao, Ding Shijin
State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China.
Sensors (Basel). 2023 Oct 2;23(19):8222. doi: 10.3390/s23198222.
Harmonic distortion is one of the dominant factors limiting the overall signal-to-noise and distortion ratio of seismic-grade sigma-delta MEMS accelerometers. This study investigates harmonic distortion based on the multiple degree-of-freedom model (MDM) established in our previous study. The main advantage of using an MDM is that the effect of finger flexibility on harmonic distortion is considered. Initially, the nonlinear relationship between the input acceleration and output signal is derived using the MDM. Then, harmonic distortion is simulated and described in terms of the nonlinear input-output relationship. It is found that finger flexibility and parasitic capacitance mismatch both decrease harmonic distortion. Finally, the experimental testing of harmonic distortion is implemented. By reducing the finger length to realize a higher stiffness and compensating for the parasitic capacitance mismatch, the total harmonic distortion decreases from -66.8 dB to -86.9 dB.
谐波失真是限制地震级∑-Δ MEMS加速度计整体信噪比和失真率的主要因素之一。本研究基于我们之前研究中建立的多自由度模型（MDM）来研究谐波失真。使用MDM的主要优点是考虑了指状物柔韧性对谐波失真的影响。首先，利用MDM推导输入加速度与输出信号之间的非线性关系。然后，根据非线性输入-输出关系对谐波失真进行模拟和描述。研究发现，指状物柔韧性和寄生电容失配都会降低谐波失真。最后，进行了谐波失真的实验测试。通过缩短指状物长度以实现更高的刚度并补偿寄生电容失配，总谐波失真从-66.8 dB降至-86.9 dB。
