Research on Design of Weak Current Measurement System Based on I-V Convertor

摘要

In this paper, after introducing several methods of measuring weak current, a weak current measurement system is designed which consists of an ultra-low bias current operation amplifier ADA4530 based on the trans-impedance amplifier topology, a secondary amplifier, an eight-order Butterworth low-pass switched-capacitor filter and other modules. Special consideration on the low noise pre-amplifier in practical applications has been proposed particularly. The simulation results of noise characteristics have shown that the system can realize the weak current measurement of μA～pA wide range.