New RSFQ circuits (Josephson junction digital devices)

Several novel circuits of the rapid single-flux-quantum (RSFQ) family of Josephson-junction digital devices have been designed, fabricated using a 2.5- mu m 1000-A/cm/sup 2/ Nb trilayer technology, and tested at low frequencies. Numerical simulation and measurements have shown that these circuits have considerably wider parameter margins, due to application of several novel design methods. The authors have also carried out an experiment to measure the rate of errors in a simple RSFQ circuit including an inverter, confluence buffer, and Josephson transmission line. Near the middle of the parameter window at 4.2 K, the error probability was definitely lower than 3*10/sup -15/ per logic operation, despite experimentation with rudimentary shielding and filtering.>