基于比率法的微电容测量仪  

Ultra Low Capacitance Measurement Instrument Based on Ratio Method

作　　者：彭建学 叶银忠[2] 刘以建[3] 李建明 

机构地区：[1]上海奥波电子有限公司,上海200070 [2]上海应用技术学院,上海200235 [3]上海海事大学物流工学院,上海200135 [4]上海精密科学仪器有限公司,上海200433

出　　处：《电测与仪表》2011年第10期64-68,共5页Electrical Measurement & Instrumentation

摘　　要：针对传统微电容测量方法的缺点提出了微电容比率测量法。采用带限流电阻的正弦波激励确保激励源和前置放大器正常工作以提高消除杂散电容的能力;检测被测电容两端的电压和流过被测电容的电流计算得到被测电容的电容值;采用锁相检测技术消除噪声和直流失调。给出了微电容测量系统的方案。实验结果表明电容测量分辨率达到了0.01pF,证明了所提出方法的有效性。A new ultra low capacitance measurement method based on the ratio is proposed against the shortcomings of the traditional measurement methods. A sinusoidat wave excitation source with a current-limiting resistor is introduced to ensure the excitation source itself and the pre-amplifier to work properly and to enhance the ability of eliminating the stray capacitances. The capacitance of the capacitor can be obtained by measuring the voltage across the capacitor and the current flowing through the capacitor. The lock-in amplifying technology is applied to eliminate the effects of the noise and the DC offset. The scheme of such ultra low capacitance measurement system is given out. The experimental results show that the resolution of the capacitance measurement reaches 0.01pF and prove the effectiveness of the proposed method.

关 键 词：微电容测量 锁相放大 杂散电容 噪声 直流失调 

分 类 号：TM934.23[电气工程—电力电子与电力传动] TP211.5[自动化与计算机技术—检测技术与自动化装置]