Event-Based Modeling of Rapid Single-Flux Quantum Basic Cells With Timing Jitter

The realizable integration level of rapid single-flux quantum (RSFQ) circuits has reached the order of magnitude of 20 000 Josephson junctions, which enables the creation of advanced complex circuits such as microprocessors or digital signal processors. During the design of those complex circuits, behavioral arrangement alone is insufficient; instead, the inclusion of statistical spread is required for timing and parameter verification. The simulation of complex circuits combined with the consideration of timing jitter effects is a very challenging task for both transient simulation on the electrical network level and simulation with hardware description languages. In this paper, a new approach based on discrete-event simulations is presented. By this method, the pulse-driven characteristics of RSFQ circuits can be directly transferred into a model describing the behavior on the transaction level. The realized models of basic RSFQ cells include stochastic timing effects. This approach is demonstrated by modeling a nontrivial cell and compared against the conventional transient simulation concerning the accuracy of the results and the computation time.