静电激励硅微机械谐振压力传感器设计

设计了一种静电激励/电容检测的硅微机械谐振压力传感器,采用改进的侧向动平衡双端固支音叉谐振器,利用基于绝缘体上硅的加工工艺制作。为了抑制压力敏感膜片受压变形时谐振器的高度变化,在谐振器固定端设计了全新的桁架结构。针对传感器检测信号微弱和同频干扰严重的特点,在芯体和接口电路设计中采取添加屏蔽电极、降低交流驱动电压幅值、差动电容检测和高频载波调制解调方案等多项措施。同时基于该接口电路设计了开环测试系统,并在常压封装条件下对传感器进行了初步性能测试。实验结果表明:其基础谐振频率为33.886 kHz,振动品质因数为1222;测量范围为表压0~280 kPa,非线性为0.018%FS,迟滞为0.176%FS,重复性为0.213%FS;在-20~60℃的温度范围内,谐振器的平均温度漂移为-0.037%/℃。

Design on electrostatically excited silicon micromachined resonant pressure sensor

A silicon micromachined resonant pressure sensor with electrostatic excitation and capacitive detection is designed, which uses improved lateral dynamically balanced double-ended tuning fork resonator. The fabrication process is based on silicon-on-insulator（SOI） wafer. Connecting truss has been developed to restrain perpendicular position shift of the resonator when the diaphragm deflects. Considering weak signal and same frequency interference in detection, several methods such as guard electrodes, reduced AC drive voltage amplitude, differential capacitive detection and scheme of high-frequency carrier modulation and demodulation is taken. Furthermore,open-loop measurement system is designed based on interface circuit, and preliminary character measurements is carried out under atmospheric pressure packaging condition. Testing results show that the fundamental resonant frequency is 33. 886 kHz, and vibration quality factor is 1222. Over the gauge pressure range of 0 -280 kPa, the nonlinearity is 0. 018 % FS, the hysteresis error is 0. 176 % FS, the repeatability is 0. 213 % FS, and the average temperature drift of the resonator is -0. 037 %/℃ at the range of -20-60 ℃.