//   Qucs analogue data voltage level shifter model (DLS_1ton).
//   Shifts from 1V to NV.
//   The structure and theoretical background to the DLS_1ton
//   Verilog-a model are presented in the Qucs mixed mode 
//   simulation tutorial.
//
//   This is free software; you can redistribute it and/or modify
//   it under the terms of the GNU General Public License as published by
//   the Free Software Foundation; either version 2, or (at your option)
//   any later version.
// 
//   Copyright (C), Mike Brinson, mbrin72043@yahoo.co.uk, December 2008.
//
`include "disciplines.vams"
`include "constants.vams"
module DLS_1ton (Lin, Lout); 
 inout Lin, Lout;
 electrical Lin, Lout;
 electrical n1, n2;
 electrical Vout;
 `define attr(txt) (*txt*)
 parameter real LEVEL = 5 from [1:inf] `attr(info= "voltage level" unit="V");
 parameter real Delay = 1e-9 from [0:inf] `attr(info="time delay" unit="s");
//
 real Rd, Cd;
//
 analog begin
  @(initial_model)
    begin
      Rd = 1e3;
      Cd= Delay*1.43/Rd;
    end
 I(n1)      <+ (V(Lin) >= 0.5) ? -LEVEL : 0;
 I(n1)      <+ V(n1);
 I(n1, n2)  <+ V(n1, n2)/Rd;
 I(n2)      <+ ddt(Cd*V(n2));
// I(Lout)    <+ -V(n2);
// I(Lout)    <+  V(Lout);
 I(Lout)    <+ V(Vout);
 I(Vout)    <+ V(Lout) - V(n2);
 end
endmodule