Josephson series arrays with NbSi barrier for ac voltage standards

The overdamped Josephson junctions for ac voltage standards are realized with Nb
_x
Si
_1-x
barriers at PTB. The characteristic parameters of the junctions can be tuned by the Nb content and the thickness over a wide range from 10 GHz to 70 GHz. The junctions are used for binary-divided 10 V arrays containing nearly 70,000 junctions and for pulse-driven arrays enabling the synthesis of pure arbitrary waveforms.