基于SQUID的直流电阻电桥指零仪设计  

Design of Null-Detector for DC Resistance Bridge Based on SQUID

作　　者：张鹏[1] 鄢志丹[1] 赵建亭[2] 鲁云峰[2] ZHANG Peng;YAN Zhi-dan;ZHAO Jian-ting;LU Yun-feng(China University of Petroleum(East China),Qingdao,Shandong 266580,China;National Institute of Metrology,Beijing 100029,China)

机构地区：[1]中国石油大学(华东),山东青岛266580 [2]中国计量科学研究院,北京100029

出　　处：《计量学报》2021年第10期1349-1353,共5页Acta Metrologica Sinica

基　　金：国家自然科学基金(51777199)。

摘　　要：设计了一款基于超导量子干涉仪(SQUID)的直流电阻电桥指零仪电路,该电路可用作高精度电阻电桥中低值电阻(0.1~100Ω)测量的指零仪电路。通过自制SQUID外围电路并优化电路其输入耦合线圈的互感值,实现微弱电桥不平衡电流的精密测量。与传统电阻电桥基于测量不平衡电压的纳伏计指零仪相比,其检测灵敏度在中低值电阻测量范围有数量级的提升。设计的作为指零仪的SQUID磁通锁定环1/f转折频率在2 Hz左右,磁通白噪声水平在3.5μφ_(0)/√Hz左右,并且输入线圈与SQUID互感系数高达10 nH,其等效的电流白噪声密度0.7 pA/√Hz。将其用作电阻电桥指零仪测量100Ω标准电阻(工作电流为10 mA)的分辨率可达到10^(-11)量级。A DC resistance bridge null-detector circuit based on superconducting quantum interferometer(SQUID)is designed.The circuit can be used as a null-detector circuit for measuring low and medium value resistance(0.1~100Ω)in high-precision resistance bridges.By making the SQUID peripheral circuit and optimizing the mutual inductance value of its input coupling coil,the precise measurement of unbalanced current of weak bridge is realized.Compared with the traditional resistance bridge based on the nanovoltmeter null-detector measuring unbalance voltage,its detection sensitivity is improved by an order of magnitude in the low-to-medium resistance measurement range.The 1/f corner frequency of SQUID flux locked loop system which is designed as a null-detector,is about 2 Hz and the white noise level of the magnetic flux is about 3.5μφ_(0)/√Hz.And the mutual inductance between input coil and SQUID is as high as 10 nH,its equivalent current white noise density 0.7 pA/√Hz.When it is used as a resistance bridge null-detector to measure 100Ωstandard resistance(operating current is 10 mA),the resolution can reach the order of 10^(-11).

关 键 词：计量学 指零仪 直流电阻电桥 超导量子干涉仪 中低值电阻 分辨率 

分 类 号：TB971[一般工业技术—计量学]