Josephson arrays at 70 GHz for conventional and programmable voltage standards

This paper describes the performance under real calibration conditions of improved conventional Nb/Al/AlO/sub x//Nb 10 V Josephson junction series arrays fabricated in the last two years at PTB. A new type of Nb/Al/AlO/sub x//Al/AlO/sub x//Al/Nb array is also described that is useful for programmable voltage standards in the frequency range from 70-90 GHz. A direct comparison with a conventional Josephson junction series array was carried out at 1.018 V. The results agree within an uncertainty of better than 1 nV.