SELF-INDUCED MAGNETIC-FIELD EFFECTS CAUSED BY EDGE CURRENTS IN PARALLEL ARRAY OF JOSEPHSON-JUNCTIONS

A transmission line consisting of a parallel connection of shunted Jos ephson junctions is one of the base elements in the new Rapid Single F lux Quantum (RSFQ) logic. When an additional bias current is applied t o the edge junction of the transmission line it generates and injects series of flux quanta on the line. This kind of pulse generators have important applications for testing RSFQ devices at high frequencies. I n such experiments unwanted steps always show up in the I-V curve of t he generator junction. This problem has been experimentally and numeri cally investigated for parallel arrays of identical junctions. Steps w ith extremely low differential resistance are found to be due to the s elf-induced magnetic field produced by the edge current. The underlyin g mechanism is that the non-uniform field divides the array into domai ns consisting of several (unit) cells each containing the same number of flux quanta. The influence of an applied homogeneous external magne tic field and a uniformly distributed bias current is also considered.