偏置电压极性对差分电容微传感器可靠工作条件的影响分析

EFFECTS OF BIAS VOLTAGE POLARITY ON RELIABLE OPERATION CONDITIONS OF DIFFERENTIAL CAPACITIVE ACCELEROMETER WITH VOLTAGE FEEDBACK

为了测得电容式传感器的电容变化,一般需要有直流偏置电压的交流驱动信号加到传感器上,然而驱动信号产生的静电力会干扰传感器的测量和可靠工作条件。文中分析差分电容传感器受到阶跃加速度信号作用时,不同偏置电压极性对可靠工作条件的影响,得到不同偏置电压极性下传感器的临界阶跃加速度与随测试信号电压和反馈系数的关系表达式及其变化曲线。结果表明若偏置电压极性为正—正或正—负配置,其电子机械反馈本质上是负反馈,且偏置电压极性为正—负配置时,传感器承受阶跃加速度冲击的能力最强。若偏置电压极性为负—负或负—正配置,其电子机械反馈本质上是正反馈,偏置电压极性为负—正配置时,其抗阶跃加速度冲击的能力最低。

For the operation of capacitive sensors, alternative electric testing signals with a dc bias voltage are needed for detecting the variation of capacitance. The electrostatic forces caused by the electric testing signal on the capacitor may interfere significantly with the measurement and the reliable operation of the devices. The effects of electric testing signal with different bias voltage polarities on the reliable operation condition are quantitatively analyzed when a step acceleration pulse is applied on the differential capacitive sensors.The dependences of the critical acceleration on testing signal level and different feedback constant are given both in expressions and in curves. It is found that the electromechanical feedback is negative in nature for positive-positive and positive-negative bias voltage configurations, and the reliable operation ranges for positive-positive bias voltage configurations is smaller that for positive-negative. The electromechanical feedback is positive in nature for negative-negative and negative-positive bias voltage configurations, and the rehable operation ranges for negative-positive bias voltage configurations is the most smaller than all other bias voltage configurations.