Research on voltage ratio for precise comparison between ac QHR and 100-kΩ resistance

At the National Metrology Institute of Japan, we are currently developing a transformer bridge circuit that can precisely compare the “i = 2” plateau resistance of an ac quantized Hall resistance with a 100-kO resistance. In this report, we propose a practical transformer voltage ratio of 7.75:1, which is the most important parameter for developing a transformer bridge circuit. Further, we describe the design of an inductive voltage divider (IVD) to realize the 7.75:1 ratio. We intend to use the proposed IVD as a reference standard for calibrating the voltage ratio of the transformer.