paramset_demo.va

`include "disciplines.vams"

// Enhancement-21 demonstration: Verilog-AMS `paramset` blocks.
//
// A `paramset <name> <target>;` defines an instantiable model `<name>` that
// behaves exactly like the target module but with selected target parameters
// *bound* to expressions (which may reference the paramset's own parameters).
// It is the Verilog-AMS way of shipping a "model library": one behavioural
// module plus several named, pre-configured variants.
//
// Here the target is a simple linear conductance `g0*(1 + k*V)` (so the model
// is mildly nonlinear and has a non-trivial AC conductance, exercising the
// autodiff Jacobian through the paramset). Three paramsets specialise it:
//
//   * res_1k     -- a fixed 1 kOhm resistor (bind r via a constant; k = 0)
//   * res_kohm   -- resistance set in kOhm through a card parameter `kohm`
//   * varistor   -- keeps g0 settable (pass-through) and binds only k

module conductor(p, n);
    inout p, n;
    electrical p, n;
    parameter real g0 = 1e-3 from (0:inf);   // linear conductance [S]
    parameter real k  = 0.0;                  // 1st-order voltage coefficient [1/V]
    analog
        I(p, n) <+ g0 * (1.0 + k * V(p, n)) * V(p, n);
endmodule

// Fixed 1 kOhm linear resistor: bind both parameters to constants.
paramset res_1k conductor;
    .g0 = 1.0e-3;
    .k  = 0.0;
endparamset

// Resistance specified in kOhm via the paramset's own card parameter `kohm`;
// the binding expression `1/(kohm*1000)` computes the conductance. `k` is
// pinned to 0 (a pure linear resistor).
paramset res_kohm conductor;
    parameter real kohm = 1.0 from (0:inf);   // resistance in kOhm
    .g0 = 1.0 / (kohm * 1000.0);
    .k  = 0.0;
endparamset

// A voltage-dependent resistor: bind only `k` (from a card parameter), and
// leave `g0` unbound so it stays settable from the model card (pass-through).
paramset varistor conductor;
    parameter real kv = 0.5;                  // voltage coefficient [1/V]
    .k = kv;
endparamset