基于比率法的微电容测量仪.pdfVIP

学兔兔 总第48卷 第550期 电测与仪表 V01．48 No．550 2011年 第lO期 Electrical Measurement＆ Instrumentation oct．2011 基于比率法的微电容测量仪 彭建学 ，叶银忠2刘以建 ，李建明4 ， (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；) 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．OlpF，证明了所提出方法的有效性。 关键词：微电容测量；锁相放大；杂散电容；噪声；直流失调 中图分类号：TM934．23，TP211．5 文献标识码：B 文章编号：1001—1390(2011)10—0064—05 Ultra Low Capacitance Measurement Instrument Based on Ratio Method 1 2 3 4 PENG Jian-xue，YE Yin-zhong，LIU Yi-jian，LI Jian-Ming (1．Shanghai Aoboor Electric CO．，Ltd．，Shanghai 200070，China．2．Shanghai Institute of Technology，Shanghai 200235， China．31 Logistics Engineering College，Shanghai Maritime Univ．，Shanghai 2001 35，China．4．Shanghai Precision Scientific Instrument CO．，Ltd．，Shanghai 200233，China．) Abstract：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