Verolig-A Code for Josephson Field-Effect Transistor Modeling.

The Verilog-A implementation corresponding to the gate-dependent compact model of the Lg = 350~nm device discussed in Sec. ~III of the journal article Device Models for Josephson Field-Effect Transistors and for Superconducting Integrated Circuits. This article was submitted to the IEEE Journal of the Electron Devices Society and is still under review. // ============================================================================// Graphene Josephson FET (JoFET) Verilog-A Model// ----------------------------------------------------------------------------// Description: // Compact Verilog-A model of a graphene-based Josephson field-effect transistor// (JoFET) based on an RCSJ formulation with gate-tunable resistance and// critical current. //// ----------------------------------------------------------------------------// Usage in ADS: //// - This model is intended to be used in Keysight ADS. // - Create a symbol from this Verilog-A module. // - Ensure the symbol is properly linked to this. va file. // - The symbol should expose three terminals: d (drain), s (source), g (gate). //// Recommended simulation setup: // * Gate (g): connect to a voltage source (Vg bias) // * Drain–Source (d–s): connect to a current source for current sweep// * Use transient simulation to observe device behavior//// ----------------------------------------------------------------------------// Notes: //// - Designed primarily for transient simulations. // - Phase dynamics implemented using time integration (idt). //// - Optional small conductance is included across d–s for numerical convergence: // I (d, s) <+ gmin * V (d, s) // This helps avoid convergence issues in ADS. It can be reduced or removed// if not required, depending on simulation stability. //// - If discipline/nature definitions are already provided by the simulator// environment (e. g. , via "disciplines. vams"), any duplicate header// Declarations should be removed to avoid redefinition errors. // Parameter Notes: // mu: carrier mobility (m²/Vs) // nr: residual carrier density (m^-2) // Rc: contact resistance (Ohm) // alpha: scaling factor for Ic// Deltaᵢnd: induced superconducting gap (J) // ----------------------------------------------------------------------------// ============================================================================