/* josephson tunnel contact model based on:
   Jaeckel,H. Baechtold,W.: "Computer-simulation models
   for digital Josephson devies and circuits" in
   Ruehli,A.E. :"Circuit Analysis, Simulation and Design"
   North-Holland,Amsterdam, New York, Oxford, Tokoy,
   1986, pp.179-205
   Model parameter provided by G.Hildebrandt, TU Ilmenau, Germany
*/

module josephson_contact(p1,p2,p3,p4);
 inout p1,p2,p3,p4;
 electrical p1,p2,p3,p4;

/* parameter set for low Tc devices (4.2Kelvin) */
 parameter real cj = 0.5p from (0.33p:1p)
                rj = 1 from (0.5:25)
                i0 = 10u from (5:1000u);

/* parameter set for high Tc devices (77Kelvin)
 parameter real cj = 0.1p from (0:0.1p)
                rj = 1 from (0.1:10)
                i0 = 10u from (2:1000u);

 real c1 = 0.329108f;

 begin
   I(p1,p2) <+ cj * ddt(V(p1,p2)) + V(p1,p2) / rj;
   I(p1,p2) <+ i0 * sin(V(p3,p4));

   I(p3,p4) <+ c1 * ddt(V(p3,p4));
   I(p3,p4) <+ -V(p1,p2);               // transadmittance=1
 end
endmodule