Modelling of the Influence of Magnetic Fields on the Operation of Digital Superconductive Circuits

We present a simulation model for analyzing and predicting magnetic field patterns and their influence on superconductive digital circuits. Unwanted magnetic fields can cause these circuits to experience reductions in operating margins or fail completely. We use InductEx to simulate the effect of running current carrying conductors around and above the circuit under study. We also use coils to mimic ambient fields. As a test bed, D-flip flops from both RSFQ and eSFQ libraries were simulated in a roughly uniform magnetic field and the coupling to every circuit inductance is recorded. From these results we construct models that link circuit inductance and by association the bias current distribution, to applied magnetic fields.