A method for improving out-of-plane robustness of an area-changed capacitive displacement transducer used in a micro-accelerometer
A method for improving out-of-plane robustness of an area-changed capacitive displacement transducer used in a micro-accelerometer
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一种提高微加速度计中变面积电容位移传感器面外鲁棒性的方法
DOI：
10.1016/j.sna.2020.112156
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Liangcheng Tu
中科院分区：
文献类型：
--
作者：
Shitao Yan;Huafeng Liu;Qiangwei Xu;D;an Liu;Mengqi Zhang;Wenjie Wu;Liangcheng Tu
变面积电容式位移传感器已广泛应用于微机电系统（MEMS）传感器中，例如MEMS加速度计，以高灵敏度检测面内位移。交叉轴干扰可能导致检测质量块的面外位移，从而带来传感电容器电极的间隙变化，并导致加速度计标度因子的不良变化。为了解决这一问题，本文提出了一种提高MEMS加速度计中变面积电容式位移传感器离面鲁棒性的新方法。芯片上的电容，敏感的检测质量的面外位移，被集成作为电荷放大器的反馈电容。因此，补偿了由交叉轴扰动引起的离面位移对标度因子的影响。通过理论计算、仿真和实验对该方法进行了验证。结果表明，当加速度作用在离面方向时，采用片上反馈电容的MEMS加速度计的交叉灵敏度小于采用片外反馈电容的1/3。此外，无论片内或片外反馈电容如何，加速度计的本底噪声都保持在60 ng/kHz。
Area-changed capacitive displacement transducers have been widely applied in micro-electro-mechanical-system (MEMS) sensors such as sandwich-type MEMS accelerometers to detect in-plane displacement with a high sensitivity. The cross-axis disturbance could result in out-of-plane displacement of the proof mass, which brings a gap variation of sensing capacitor electrodes and lead to an undesirable variation of the accelerometer’s scale factor. In order to solve this problem, this paper presents a novel method to improve out-of-plane robustness of an Area-changed capacitive displacement transducer in a MEMS accelerometer. An on-chip capacitor, sensitive to the out-of-plane displacement of proof mass, was integrated as the feedback capacitor of the charge amplifier. Thus, the influence of the out-of-plane displacement on the scale factor caused by cross-axis disturbance is compensated. The method was verified by theoretical calculation, simulation and experiments. The results indicated that the cross-sensitivity of the MEMS accelerometer with an on-chip feedback capacitor was less than 1/3 of that with off-chip feedback capacitor when acceleration was applied on the out-of-plane direction. Besides, the noise floor of the accelerometer maintained at 60 ng/√Hz regardless of the on-chip or off-chip feedback capacitors.