RSFQ DC to SFQ Converter with Reduced Josephson Current Density

In this paper we consider the Rapid Single-Flux Quantum (RSFQ) circuits with reduced Josephson current density and especially deal with one of the basic building blocks of these electronics the DC to SFQ converter. For future promising RSFQ applications the critical current of the Josephson junctions should be reduced (by reduction of Josephson current density) to several μA, resulting into values of the interferometer’s inductance of several hundreds of pH. Such large inductances cannot be efficiently realized and we utilize an approach for substitution of inductances by arrays of classical Josephson junctions operating in nonswitching mode. We investigate the classical DC to SFQ converter and based on the utilized approach we design a new schematic with reduced Josephson current density. The circuit is optimized with respect to yield and fabrication margins of the design parameters. Key-Words: Superconductivity, Rapid Single-Flux Quantum (RSFQ) electronics, Josephson junction, DC to SFQ converter.