introduce jfet gate-drain and gate-source junction emission coefficient

src/spicelib/devices/jfet/jfet.c

@@ -62,6 +62,7 @@ IFparm JFETmPTable[] = { /* model parameters */
  IOPA("cgd",     JFET_MOD_CGD,    IF_REAL,"G-D junction cap"),
  IOP("pb",      JFET_MOD_PB,      IF_REAL,"Gate junction potential"),
  IOP("is",      JFET_MOD_IS,      IF_REAL,"Gate junction saturation current"),
+ IOP("n", JFET_MOD_N,   IF_REAL, "Emission Coefficient for gate-drain and gate-source diodes"),
  IOP("fc",      JFET_MOD_FC,      IF_REAL,"Forward bias junction fit parm."),
  /* Modification for Sydney University JFET model */
  IOP("b",     JFET_MOD_B,        IF_REAL,"Doping tail parameter"),

src/spicelib/devices/jfet/jfetdefs.h

@@ -211,6 +211,7 @@ typedef struct sJFETmodel {       /* model structure for a jfet */
     double JFETcapGD;
     double JFETgatePotential;
     double JFETgateSatCurrent;
+    double JFETemissionCoeff;
     double JFETdepletionCapCoeff;
     double JFETfNcoef;
     double JFETfNexp;
@@ -242,6 +243,7 @@ typedef struct sJFETmodel {       /* model structure for a jfet */
     unsigned JFETcapGDGiven : 1;
     unsigned JFETgatePotentialGiven : 1;
     unsigned JFETgateSatCurrentGiven : 1;
+    unsigned JFETemissionCoeffGiven: 1;
     unsigned JFETdepletionCapCoeffGiven : 1;
     /* Modification for Sydney University JFET model */
     unsigned JFETbGiven : 1;
@@ -290,6 +292,7 @@ enum {
     JFET_MOD_CGD,
     JFET_MOD_PB,
     JFET_MOD_IS,
+    JFET_MOD_N,
     JFET_MOD_FC,
     JFET_MOD_NJF,
     JFET_MOD_PJF,

src/spicelib/devices/jfet/jfetload.c

@@ -224,7 +224,7 @@ JFETload(GENmodel *inModel, CKTcircuit *ckt)
              */
             vds=vgs-vgd;
             
-            vt_temp=here->JFETtemp*CONSTKoverQ;
+            vt_temp=here->JFETtemp*CONSTKoverQ*model->JFETemissionCoeff;
             if (vgs < -3*vt_temp) {
                 arg=3*vt_temp/(vgs*CONSTe);
                 arg = arg * arg * arg;

src/spicelib/devices/jfet/jfetmask.c

@@ -62,6 +62,9 @@ JFETmAsk(CKTcircuit *ckt, GENmodel *inModel, int which, IFvalue *value)
         case JFET_MOD_IS:
             value->rValue = model->JFETgateSatCurrent;
             return(OK);
+        case JFET_MOD_N:
+            value->rValue = model->JFETemissionCoeff;
+            return(OK);
         case JFET_MOD_FC:
             value->rValue = model->JFETdepletionCapCoeff;
             return(OK);

src/spicelib/devices/jfet/jfetmpar.c

@@ -58,6 +58,10 @@ JFETmParam(int param, IFvalue *value, GENmodel *inModels)
             model->JFETgateSatCurrentGiven = TRUE;
             model->JFETgateSatCurrent = value->rValue;
             break;
+        case JFET_MOD_N:
+            model->JFETemissionCoeff = value->rValue;
+            model->JFETemissionCoeffGiven = TRUE;
+            break;
         case JFET_MOD_FC:
             model->JFETdepletionCapCoeffGiven = TRUE;
             model->JFETdepletionCapCoeff = value->rValue;

src/spicelib/devices/jfet/jfetset.c

@@ -59,6 +59,9 @@ JFETsetup(SMPmatrix *matrix, GENmodel *inModel, CKTcircuit *ckt, int *states)
         if(!model->JFETgateSatCurrentGiven) {
             model->JFETgateSatCurrent = 1e-14;
         }
+        if(!model->JFETemissionCoeffGiven) {
+            model->JFETemissionCoeff = 1;
+        }
         if(!model->JFETdepletionCapCoeffGiven) {
             model->JFETdepletionCapCoeff = .5;
         }

src/spicelib/devices/jfet/jfettemp.c

@@ -22,7 +22,7 @@ JFETtemp(GENmodel *inModel, CKTcircuit *ckt)
     JFETmodel *model = (JFETmodel*)inModel;
     JFETinstance *here;
     double xfc;
-    double vt;
+    double vt, vtn;
     double vtnom;
     double kt,kt1;
     double arg,arg1;
@@ -87,12 +87,13 @@ JFETtemp(GENmodel *inModel, CKTcircuit *ckt)
                 here->JFETtemp = ckt->CKTtemp + here->JFETdtemp;
             }
             vt = here->JFETtemp * CONSTKoverQ;
+            vtn = vt * model->JFETemissionCoeff;
             fact2 = here->JFETtemp/REFTEMP;
             ratio1 = here->JFETtemp/model->JFETtnom -1;
             if (model->JFETxtiGiven) {
-                here->JFETtSatCur = model->JFETgateSatCurrent * exp(ratio1*model->JFETeg/vt) * pow(ratio1+1,model->JFETxti);
+                here->JFETtSatCur = model->JFETgateSatCurrent * exp(ratio1*model->JFETeg/vtn) * pow(ratio1+1,model->JFETxti);
             } else {
-                here->JFETtSatCur = model->JFETgateSatCurrent * exp(ratio1*model->JFETeg/vt);
+                here->JFETtSatCur = model->JFETgateSatCurrent * exp(ratio1*model->JFETeg/vtn);
             }
             here->JFETtCGS = model->JFETcapGS * cjfact;
             here->JFETtCGD = model->JFETcapGD * cjfact;