Realization of Absolute Phase and AC Resistance of Current Shunts by Ratio Measurements

This paper presents a simplified method for realizing absolute phase and ac resistance for current shunts using only impedance ratio measurements. The method is based on three geometrically identical current shunts with different resistances, but with the same inductance, capacitance, and ac-dc resistance change. We demonstrate how the inductance, capacitance, and ac resistance can be calculated from the complex impedance ratio measurements, therefore realizing absolute current shunt impedance. The method gives competitive uncertainties of around 200 μQ/Q for amplitude and 400 μrad for phase at 1 MHz in the 1-Q range.