高阻抗微弱信号测量的保护电路设计

Design of Guard Circuit for High Impedance Weak Signal Measurement

针对高阻抗微弱信号测量问题,对测量精度与系统输入阻抗、输入偏置电流的关系进行分析,应用保护技术设计了带保护电路的测量电路,将电路中的低阻抗节点加上保护电势,减小漏电流的影响。通过PSpice仿真分析,验证保护电路能提高测量系统的输入阻抗和降低输入偏置电流,结果表明保护电路技术能实现对高阻抗微弱信号的高精度测量。

Aining at high impedance weak signal measurement, the relations among measuring precision, input impedance and input bias current,the guard technology is applied to design a measuring circuit with guard circuit,adding a guard potential to low -impedance nodes of circuit, the effect of leakage current is reduced. Using Spice simulation and validates that guard circuit can increase the input impedance of the system and lower the input bias current, the results show that the guard circuit provids a valuable solution for high accuracy measurement of the high impedance weak signal.