ULTIMATE PERFORMANCE OF THE RSFQ LOGIC CIRCUITS.

A family of dc-powered Josephson junction digital devices, the rapid single flux quantum (RSFQ) logic, is described. The devices use overdamped Josephson junctions and two-junction interferometers to store, pass and process digital information presented in form of single flux quanta. The authors have carried out extensive numerical simulation of the dynamics of the RSFQ logic gates and of some more complex circuits, including a serial full adder and a reversible shift register, within the standard microscopic-theory (Werthamer) description of Josephson junctions. The minimum clock cycles of the basic RSFQ circuits turn out to be as small as 2. 5 ps. The most promising ways to use the RSFQ logic circuit at the present stage of development of the Josephson junction digital technology are discussed.