采用电压跟随结构的精密电流检测系统设计

Design of precision current detecting system with voltage following structure

设计了一种基于电阻采样法的电流检测系统。在电流检测电路和A/D电路之间设计了电压跟随结构以消除A/D电路对电流检测过程的扰动。系统地分析了电流检测的误差来源,其主要由取样电阻器的误差、运放失调电压和ADC的失调误差三部分造成,其中运放失调电压是主要的误差来源。测试结果表明:所设计的电流检测电路可实现电流的实时检测,电流测量精度达到10μA,测量误差率小于5%。

A current detecting system based on resistance sampling method is designed.The voltage following structure is designed between the current detecting circuit and the A/D circuit eliminates disturbance effect from A/D circuit to current detecting process.Source of errors in current detecting are systematically analyzed,theoretical analysis shows that the system errors are caused by sampling resistor,offset voltage of operational amplifier and offset error of ADC VM,and offset voltage,among them,Vos is the main source of errors.Test results show that,the proposed current detecting circuit can achieve real-time detection of current,the detection precision of current is 10μA,and the measurement error rate is lower than 5%.