Shunted bicrystal Josephson junctions arrays for voltage standards

Series arrays of 365 shunted YBa2CU3O7-x Josephson junctions on yttria-stabilized zirconia bicrystals were investigated under microwave irradiation in the K-band. Sub-arrays of up to 39 junctions were synchronized to the external microwave power at a temperature of 15 K. Although there was a considerable spread in the critical currents of the junctions and in the microwave bias current distribution, a first Shapiro step with a height of 30% of the total critical current of the sub-array was obtained by using an external shunt resistor, thus reducing the spread in normal resistances to 5%. Such high-T-c cryoelectronic circuits are applicable for voltage standards and precision digital-analog converters. (C) 1996 American Institute of Physics.