HYBRID INTEGRATION OF A JOSEPHSON SERIES ARRAY AND A 10 GHZ PLANAR OSCILLATOR

A computer-controlled Josephson voltage standard has been developed co mprising the hybrid integration of a planar oscillator and a Josephson series array, A 10 GHz voltage-controlled oscillator has been frequen cy-stabilized to a reference frequency by a phase-locked loop, A serie s array has been designed and fabricated in Nb/Al2O3/Nb technology, To obtain quantized voltage steps with a drive frequency of 10 GHz, the critical current density of the junctions is reduced to below 2 A/cm(2 ) by variation of the oxidation parameters. The hg brid integration of a Josephson circuit with a planar MESFET oscillator produced quantize d voltage steps up to 980 mV with a step width of 2 mu A.