Development of 7.75 Ratio Voltage Divider Toward a Precise Measurement of Decade Resistance Based on the AC Quantized Hall Resistance

At the National Metrology Institute of Japan, we are developing a transformer bridge circuit that can precisely compare the i = 2 plateau resistance in an ac quantized Hall resistance with a 100-kQ resistance. In this paper, 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. The reference IVD was fabricated with the two-stage technique and calibrated by Thompson's method. The deviation from the nominal ratio of 7.75 was estimated to be -5.92×10
^-6
for in-phase and -22.75×10
^-6
for quadrature. The standard uncertainty of this calibration was estimated to be 0.63 × 10
^-6
for in-phase and 6.28 × 10
^-6
for quadrature.