Dc Micro-current Standard Source Design

With the development of science and technology, micro electric current detectiontechnology has extensive application prospect in many fields, is of great significance topromote the development of related fields. Because dc current measuring instrumentverification is required, so this topic research on dc micro current standard source hasthe vital significance.This paper based on micro electric current test instrument and the study of microcurrent source analyzes the implementation scheme of dc micro current source,according to the verification requirements and components characteristics, in differentoutput range, respectively use current feedback mode and pulse width approach todesign. In this paper, operational amplifier is adopted to form negative feedback circuit,can adapt to the107load; Produced by pulse adjustable wide slope gentle but fixedline voltage through differential capacitance, pulse wide tuning range under10-9A awayto achieve the output current; With wide pulse adjustable programmable divider isdesigned to adjust size. In addition, this article also discusses the filter design, test plan,etc.Through the simulation and experimental validation, circuit system can realize thebasic function.Micro current measurement technology was discussed and the status quo andfeatures of micro current measurement instrument, analyzed the main micro currentsource technology characteristics, this paper introduces the current negative feedbackscheme with the pulse width control signal generation, discusses the characteristics ofbutterworth low-pass filter and the circuit design. Hardware, software designenvironment is described in detail. Put forward some feasible test methods for microcurrent source.