Josephson arrays containing 2000 and 20thinsp;160 Nb/Al2O3/Nb tunnel junctions produce stable quantized voltage steps up to 1.5 and 14.5 V, respectively, with current amplitudes on the order of 100 mgr;A. In precision measurements these voltage steps proved to be stable for typically 30 min. Fabricating the voltage standards with the help of the Nb/Al2O3/Nb technology results in a long durability.
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