ANALYSIS OF RESISTANCE VS. VOLTAGE DEPENDENCE IN LOW VOLTAGE REGIONS FOR PRECISION VALUE RESISTORS

摘要

Modern advanced electronic equipment, especially measuring, widely utilizes high ohmic resistors and resistive networks. While furnished with semiconductors, especially the MOS-FET ones - the measuring circuits are generally powered by low DC voltages, usually not exceeding several tens of volts. So then voltages applied across the cooperating high ohmic resistors, voltage dividers and other type networks also do not exceed this value. That is the reason, why the behaviour of high ohmic resistors in low voltage regions of alimentation becomes a factor of highest importance in cases of precision voltage dividers and feed-back networks. Here the main point is the nonlinearity of resistance as a function of applied voltage, as well as the resistance unstability, depending on period of life, temperature, humidity etc. The presented work is focussed on VCR problems in high ohmic resistors, occurring in the (H-200V DC voltage range. Such a range covers all practical cases of nonlinearity and unstability of these resistors. According to the introduced highly sophisticated computer measuring methods - the work presents numerous graphs of resistance vs. voltage plots for several typical resistive film materials and resistor manufacturing techniques. The obtained results permit to choose the proper resistor type and its most favourable exploitation conditions. Ways and methods of minimizing the VCR value of resistors are discussed.