Josephson voltage standard cryoelectronic circuits in Nb/Al/sub 2/O/sub 3//Nb technology operating at low drive frequencies

A new type of cryoelectronic microwave circuits in Nb/Al/sub 2/O/sub 3//Nb technology for the generation of frequency-scaled Josephson voltages is presented. The circuits consist of superconducting microstripline resonators with series arrays of Josephson tunnel junctions located on the rf current antinodes. The circuits are designed to obtain highly accurate Josephson voltages at low rf power levels and low drive frequencies. At present, we have observed Josephson voltages up to 0.66 V in a resonator circuit with 1456 junctions.