Optimization of Measuring Current for Chopper Low Resistance Comparator

The article describes systematic error analysis for realized chopper low-resistance comparator. The objective was to determine optimal working conditions, considering limited resolution (about 10 nV) and resistance variation due to self-heating caused by increase of measuring current. The analysis and performances of realized chopper low-resistance comparator prototype instrument confirmed the initial assumptions of applied principles. The error for 1 A measuring current is 1.15 ppm in the measuring range of 10 mΩ. It is possible to use the same principle for calculation of optimal measuring current and measurement error in other measurement ranges, as well.