恒流源在高精度数字多用表中的设计与实现

Design and Realization of Constant Current Source in the High-Precision DMM

针对高精度数字多用表中的电阻测量功能,设计了一种高稳定度的恒流源。通过分析典型的恒流源的电路结构和工作原理,研究了影响恒流源精度的一些关键因素,提出了恒流源的设计方案,该方案采用由低噪声的运算放大器构成的反馈型电路来设计,给出了具体的硬件原理图。实验结果表明:设计的恒流源能够满足高精度的数字多用表中电阻测量功能应用。该电路具有较小的体积和高可靠性,设计方式灵活,具有很好的使用价值。

Constant current source with high stability is designed for the resistance measurement function of highprecision digital multi-meter. By analyzing the typical constant current source circuit structure and working principle and some key factors impacting on the constant current source accuracy, constant current source was designed in use of feedback low noise operational amplifier-based circuit and gave the specific schematic. The results show that the constant current source meets resistance measurement function of DMM. The circuit has small size, high reliability and design flexibility, so it has a very good value.