摘要
nA级电流检测电路是扫描隧道显微系统的重要组成部分。为更准确地提取和测量隧道电流信号,设计了一种基于高精度运放的nA级电流放大和检测电路,检测电路根据反馈电流放大型测量原理设计。为减小噪声干扰、提高测量结果的稳定性,采用分散放大倍数的两级放大电路设计,根据所要消除的噪声特点在测量电路中加入了带阻滤波电路,并针对电路板设计和制作过程采用了一些硬件抗干扰措施,同时在软件设计中加入数字滤波算法,以减少高频噪声干扰。实验表明,电路测量精度到达0.1nA,测量系统的动态响应特性良好,且具有较强的抗干扰能力。
An nA level current measuring circuit is important for a scanning tunneling microscope system. To improve the precision of the extration and measurement, an nA level current measuring circuit based on high precision amplifiers was designed as a two-stage amplifying structure. The circuit is designed on the basis of the current-amplifying I/V transition method. The band rejection filter and digital filter were adopted. To reduce noise interference, some hardware anti- jamming ways were introduced in the design and facture of the PCB. A series of Gaussian digital approximation filters were used in the A/D program designed on the basis of the approximation method and bilinear transformation. The measurement results show that the circuit can be obtained to an accuracy of one nano-ampere and has capacity of resisting interference.
出处
《微纳电子技术》
CAS
2008年第7期419-422,共4页
Micronanoelectronic Technology
关键词
数字滤波
抗干扰
纳安级电流
I/V变换
两级放大
digital filter
anti-jamming
nA level current
I/V transition
two-stage amplifying
