全数字低温漂差动电容检测技术

Low temperature drift digital detector for differential capacitances

为降低微小差动电容检测电路的复杂度,提高检测结果的温度稳定性,提出了一种结构简单,无需移相器、滤波器、解调器的全数字检测硬件平台;然后以此硬件平台为基础,设计了检测结果与检测激励信号幅值无关,无需稳幅及温度补偿电路的检测算法。将该技术应用于某差动电容型电子水平仪进行一次启动长期稳定性试验,结果表明在连续24 h内温度变化达12℃时,水平仪的输出变化不超过±1个字(±0.5″),具有优异的温度稳定特性。该技术还可应用于其他任意采用单频正弦信号进行激励的微弱信号检测,如动调陀螺信号检测、微位移传感器信号检测等。

To reduce the complexity of differential capacitance detecting circuits and improve the temperature stability of the detecting results, a new all-digital detecting platform without hardware phase shifter, filter and demodulator is presented. Based on this hardware platform, a detecting algorithm is given. The amplitude of activating signal has no effect on the detecting result of this algorithm, so the amplitude stabilizing and temperature compensating circuit for activating signal can be removed. Long-term stability of a digital level gauge using this detecting technology is tested, showing that the error doesn＇t exceed 4-1LSB （±0.5＂ ） when temperature variation reaches to 12℃ during 24 h. This detecting technology can also be used for the weak signal detectors adopting single frequency sinusoidal activating signal, such as dynamically tuned gyroscope detector and small displacement detector.