Josephson 8-bit shift register

A Josephson 8-bit shift register for use in Josephson computers and signal processors is described. The gates used in the circuit are modified variable threshold logic (MVTL) gates fabricated by 2.5-/spl mu/m Nb/AlO/SUB x//Nb junction technology with Mo resistors and SiO/SUB 2/ insulation. They are driven by a three-phase power supply. The shift register has 112 gates and occupies a 1.1/spl times/2.1-mm/SUP 2/ area. Correct shift, load, hold, and clear operations were experimentally confirmed for all bits. The circuit operated at a clock frequency up to 2.3 GHz. Its power consumption was 1.8 mW. This power level is two or three orders of magnitude lower than for Si or GaAs shift registers.