An automated 55 GHz cryogenic Josephson sampling oscilloscope

A computer-automated superconductive 55 GHz sampling oscilloscope based on 4 kA/cm2, Nb/Nb2O5/Pb edge Josephson junctions is presented. The Josephson sampler chip was flip-chip bonded to a carrier chip with a coplanar transmission line by use of a novel flip-chip bonding machine. A 5.6 ps step pulse was successfully coupled in to the transmission line and 18.5 GHz multiple reflections plus a parasitic oscillation at 43 GHz were observed.