On the development of large Josephson series arrays for voltage standards of high precision

It is possible to obtain stable reference voltages of more than 1 V for high-precision voltage standards by generating microwave-induced zero current constant voltage steps in the dc characteristic of large series arrays of Josephson tunnel junctions. An array voltage of 1 V can be reproduced within a few parts in 10¹⁰ at room temperature. The current dependence of the step voltage at the 1-V level over a stepwidth of 20 μA is less than 7 × 10⁻¹³V.