电荷平衡式电容传感器的研究

本文介绍电荷平衡式电容传感器位移测量系统的原理、结构和系统设计。本系统采用特殊设计的三积分A/D转换器,使仪器的分辨率达二十五万分之一,采样速率达50次/s以上。本文对传感器、三积分A/D转换器等关键部分均作了详细分析和设计。

A Charge Balance Capacity Sensor

The constructional and operational principles of a kind of electric ch- arge balance displacement system are introduced in this paper. The design method of the sensor, the pre-amplifier and the high speed, high accuracy A/D con- verter are also discussed. As the output signal of the sensor is obtained by compar- ing the measuring capacitor with the reference one, the dielectric constant of the capacitor has no influence on the output of the sensor. The detecting circuit works in the manner of full feedback and in the zero-voltage position, which makes the amplitude and the frequency of the exciting voltage exert no influence on the output signal, so the system maintains high accuracy and high stability. The linea- rity of the system is better than 1/10,000, the stability is 2/100,000, within 24hrs, and the vesolution is 4/1,000,000.