  Josephson junction circuits, such as superconducting quantum interference
devices (SQUIDs) and single-flux-quantum (SFQ) circuits, have been successfully
applied in both analog and digital electronic domains. They are considered to
be distinct from the normal resistor-inductor-capacitor (RLC) circuits, due to
the superconducting physics. To bridge the gap between Josephson junction
circuits and conventional RLC circuits, we introduce a magnetic-flux-generator
(MFG) model to unify the definitions of Josephson junctions and normal
noninductive components, and transform their circuits uniformly into MFG
networks. A general network equation for both superconducting and normal MFG
networks is derived. It shows that, Josephson junction circuits are the
superconducting RLC networks modulated by Josephson currents; their analysis
and simulation are unified with that of the normal RLC circuits by solving the
general network equation.
