Design of RSFQ Circuits with high- Tc and low-Tc Superconductors

Dr. Hannes Töpfer, Technische Universität Ilmenau, Fakultät für Elektrotechnik und Informationstechnik, Institut für Allgemeine und Theoretische Elektrotechnik, Postfach 0565, D-98684 Ilmenau, Germany, e-mail:, WWW:

The significant progress in the development of Rapid Single Flux Quantum (RSFQ) logic circuits indicates their potential for fast cryoelectronic device applications. A key prerequisite for any successful implementation is the availability of a comprehensive support by several computer-aided design techniques.
The possibilities of realizing RSFQ components with high-Tc superconductive materials have been studied by means of numerical computations. The most crucial task is to manage the trade-off between desired high critical currents and the loop inductances, which cannot be made arbitrarily small. Parameter extractions for typical layout arrangements and dynamical simulations including thermal noise give justification for expecting small scale high-Tc implementations.
Recently, software solutions for supporting the design at several stages of its cycle have been elaborated. They address topics like computation of inductances, broadband characterization of pulse transmitting structures, influence of noise on circuit operation, yield driven optimization as well as cell-based logic synthesis of considerable complexity. The analysis and design facilities are described and illustrated by means of typical results.