SPICE models and applications of superconducting FETs and higher-voltage Josephson gates

The authors describe the development of circuit models, applications of superconducting field effect transistors (SFETs), and higher-voltage Josephson junction (HVJJ) circuits which are important for the feasibility of several novel hybrid superconducting-semiconducting circuits. They also discuss the delay optimization involved in designing and embedding interface circuits in a hybrid superconductor-semiconductor technology. It is noted that, with the advances made in semiconductor technologies, interfaces between the two technologies are practical now and the advantages of hybrid circuits in various applications should be realizable in practice. In the case of interfacing typical Nb-based Josephson junction circuits to 0.5 mu m CMOS technologies, it was estimated that the minimum delay through the interface is approximately 110 ps and the optimum number of junctions in each branch of the HVJJ circuits is 10.<>