Superconductive circuits and the general-purpose electronic simulator APLAC

The general-purpose circuit simulator analysis program for linear active circuits (APLAC) is not widely known within the superconductor circuit community, regardless of its built-in Josephson junction model and capability of modeling the superconductive phase transition with controlled sources. We review the use of APLAC to model, e.g., noisy dc SQUIDs and transition-edge sensors. Based on an APLAC simulation, we also comment on the preference of voltage bias over current bias in dc SQUIDs in applications where large dynamic range and high bandwidth are simultaneously required.