Automated Voltage-Ratio Measurement for Resistance Calibration

The development of an automatic calibration system is conducive to getting very effective measurement results and convenient use, especially for resistance calibration by using the voltage-ratio method based on Ohm's law. By this method, the referent current is biased through two resistors (known and unknown resistors) to evaluate the voltage ratio value. Based on the comparative ratios of voltage and resistance values, the unknown resistance can be calculated. Therefore, the high stability of the referent current bias and the simultaneous voltage measurement between two resistors should be considered. In this work, an automatic calibration system is developed via LabView for resistance calibration using the referent current in the range of 1 µA to 200 A. The developed software can work effectively based on the software validation. The stability of the bias current is within the instrument manufacturer's specifications measured by the developed software.