An AC Josephson Voltage Standard up to the Kilohertz Range Tested in a Calibration Laboratory

This paper describes the development of an automated ac quantum voltmeter toward a turnkey system, which can be used for calibration of common dc and ac voltage standards. The setup was tested in an accredited commercial calibration laboratory to characterize Fluke 5700A calibrators and voltage standards. The measured voltage in dependence on various parameters is presented in the range of dc to 2 kHz with amplitudes up to 10 V. The uncertainty components are discussed, and the system relevant Type B uncertainty for ac voltage calibrations is 0.15 μV/V. The contribution of the leakage current is investigated in detail and found to be notable for frequencies above 1 kHz due to parasitic capacitances. The combined measurement uncertainty for calibration ac voltages is less than 0.62 μV/V (k = 1 and 40 Hz-1 kHz) and is limited by the noise of the calibrator. Comparison measurements at Physikalisch-Technische Bundesanstalt have been done and confirm the system reproducibility.

I. Introduction

In recent years, programmable Josephson arrays [1], [2] have become very attractive for the ac voltage metrology. Sampling techniques [3]–[6] and locked synthesizer methods [7] are used to eliminate the effect of parasitic transients [8], [9] when measuring ac waveforms with this type of Josephson arrays. There is demand for such systems by not only National Metrology Institutes but also commercial calibration providers.