基于低温电流比较仪的微弱电流放大器设计  

Design of weak current amplifier based on the cryogenic current comparator

作　　者：丁立 鲁云峰[2,3] 赵建亭 鄢志丹[1] 贺青 Ding Li;Lu Yunfeng;Zhao Jianting;Yan Zhidan;He Qing(College of Control Science and Engineering,China University of Petroleum(East China),Qingdao 266000,China;Division of Electricity and Magnetism,National Institute of Metrology,Beijing 100029 China;Key Laboratory of Electrical Quantum Standards for State Market Regulation,Beijing 100029 China)

机构地区：[1]中国石油大学(华东)控制科学与工程学院,青岛266000 [2]中国计量科学研究院电磁所,北京100029 [3]国家市场监管重点实验室(电学量子基准),北京100029

出　　处：《仪器仪表学报》2022年第5期86-92,共7页Chinese Journal of Scientific Instrument

基　　金：中国科学院战略性先导科技专项(XDC07010100);国家自然科学基金(51777199)项目资助。

摘　　要：文章设计并制作了一款基于低温电流比较仪(CCC)的低噪声电流放大器,可以用于pA量级微弱电流的精密测量。该放大器由最大匝比2000∶1的超导比例线圈、直流超导量子干涉器以及超导屏蔽等组成,建立了该放大器等效输入电流噪声、电流灵敏度以及反馈回路模型,在此基础上提出了降低放大器噪声和提高放大器灵敏度的方法。实验结果表明,CCC超导比例线圈与匝数为12的检测线圈的耦合系数可以达到0.61,当CCC电流放大比例为2000∶1时,在1 Hz频率下,放大器的等效输入电流噪声为30 fA/Hz^(0.5),电流灵敏度为4.71 nA/Φ_(0),该放大器的性能在对峰峰值为6 pA的方波电流测试中得到了验证。A low noise current amplifier based on the cryogenic current comparator(CCC)is designed and fabricated,which can be used for precision measurement of pA level weak current.The amplifier consists of superconducting proportional coils with a maximum turn ratio of 2000∶1,a DC-superconducting quantum interference device and a superconducting shield.The equivalent input current noise,current sensitivity and feedback loop model of the amplifier are established.On this basis,the methods to reduce the amplifier noise and improve the amplifier sensitivity are proposed.Experimental results show that the coupling coefficient between CCC superconducting proportional coils and pick-up coil with 12 turns is 0.61.When the CCC current amplification ratio is 2000∶1,the equivalent input current noise of the amplifier is 30 fA/Hz^(0.5) at 1 Hz.The current sensitivity is 4.71 nA/Φ_(0) and the performance of the amplifier has been evaluated in the test of peak to peak 6 pA square wave current.

关 键 词：低温电流比较仪 直流超导量子干涉仪 电流放大器 低噪声 微弱电流 

分 类 号：TB971[一般工业技术—计量学] TH89[机械工程—测试计量技术及仪器]