introduce IBE and IBC model parameter for more accurate current calculation

src/spicelib/devices/bjt/bjt.c

@@ -82,6 +82,8 @@ IFparm BJTmPTable[] = { /* model parameters */
  IOP("tnom", BJT_MOD_TNOM, IF_REAL, "Parameter measurement temperature"),
  IOPR("tref", BJT_MOD_TNOM, IF_REAL, "Parameter measurement temperature"),
  IOP("is",   BJT_MOD_IS,   IF_REAL, "Saturation Current"),
+ IOP("ibe",  BJT_MOD_IBE,  IF_REAL, "Base-Emitter saturation Current"),
+ IOP("ibc",  BJT_MOD_IBC,  IF_REAL, "Base-Collector saturation Current"),
  IOP("bf",   BJT_MOD_BF,   IF_REAL, "Ideal forward beta"),
  IOP("nf",   BJT_MOD_NF,   IF_REAL, "Forward emission coefficient"),
  IOP("vaf",  BJT_MOD_VAF,  IF_REAL, "Forward Early voltage"),

src/spicelib/devices/bjt/bjtdefs.h

@@ -60,6 +60,8 @@ typedef struct sBJTinstance {
     double BJTtemp;     /* instance temperature */
     double BJTdtemp;     /* instance delta temperature from circuit */
     double BJTtSatCur;  /* temperature adjusted saturation current */
+    double BJTBEtSatCur;  /* temperature adjusted saturation current */
+    double BJTBCtSatCur;  /* temperature adjusted saturation current */
     double BJTtBetaF;   /* temperature adjusted forward beta */
     double BJTtBetaR;   /* temperature adjusted reverse beta */
     double BJTtBEleakCur;  /* temperature adjusted B-E leakage current */
@@ -371,6 +373,8 @@ typedef struct sBJTmodel {          /* model structure for a bjt */
 
     double BJTtnom; /* nominal temperature */
     double BJTsatCur;   /* input - don't use */
+    double BJTBEsatCur;
+    double BJTBCsatCur;
     double BJTbetaF;    /* input - don't use */
     double BJTemissionCoeffF;
     double BJTearlyVoltF;
@@ -505,6 +509,8 @@ typedef struct sBJTmodel {          /* model structure for a bjt */
     unsigned BJTsubsGiven : 1;
     unsigned BJTtnomGiven : 1;
     unsigned BJTsatCurGiven : 1;
+    unsigned BJTBEsatCurGiven : 1;
+    unsigned BJTBCsatCurGiven : 1;
     unsigned BJTbetaFGiven : 1;
     unsigned BJTemissionCoeffFGiven : 1;
     unsigned BJTearlyVoltFGiven : 1;
@@ -659,6 +665,8 @@ enum {
     BJT_MOD_NPN = 101,
     BJT_MOD_PNP,
     BJT_MOD_IS,
+    BJT_MOD_IBE,
+    BJT_MOD_IBC,
     BJT_MOD_BF,
     BJT_MOD_NF,
     BJT_MOD_VAF,

src/spicelib/devices/bjt/bjtdset.c

@@ -35,7 +35,7 @@ int BJTdSetup(GENmodel *inModel, CKTcircuit *ckt)
     double cbe;
     double cben;
     double cdis;
-    double csat;
+    double csatbe, csatbc;
     double ctot;
     double czbc;
     double czbcf2;
@@ -153,7 +153,8 @@ int BJTdSetup(GENmodel *inModel, CKTcircuit *ckt)
             /*
              *   dc model paramters
              */
-            csat=here->BJTtSatCur*here->BJTarea * here->BJTm;
+            csatbe=here->BJTBEtSatCur*here->BJTarea * here->BJTm;
+            csatbc=here->BJTBCtSatCur*here->BJTarea * here->BJTm;
             rbpr=here->BJTtminBaseResist/(here->BJTarea * here->BJTm);
             rbpi=here->BJTtbaseResist/(here->BJTarea * here->BJTm)-rbpr;
             oik=here->BJTtinvRollOffF/(here->BJTarea * here->BJTm);
@@ -228,9 +229,9 @@ int BJTdSetup(GENmodel *inModel, CKTcircuit *ckt)
             vtn=vt*here->BJTtemissionCoeffF;
             if(vbe > -5*vtn){
                 evbe=exp(vbe/vtn);
-                cbe=csat*(evbe-1)+ckt->CKTgmin*vbe;
-                gbe=csat*evbe/vtn+ckt->CKTgmin;
-                gbe2 = csat*evbe/vtn/vtn;
+                cbe=csatbe*(evbe-1)+ckt->CKTgmin*vbe;
+                gbe=csatbe*evbe/vtn+ckt->CKTgmin;
+                gbe2 = csatbe*evbe/vtn/vtn;
                 gbe3 = gbe2/vtn;
 
                 /* note - these are actually derivs, not Taylor
@@ -247,7 +248,7 @@ int BJTdSetup(GENmodel *inModel, CKTcircuit *ckt)
                     gben3=gben2/vte;
                 }
             } else {
-                gbe = -csat/vbe+ckt->CKTgmin;
+                gbe = -csatbe/vbe+ckt->CKTgmin;
                 gbe2=gbe3=gben2=gben3=0;
                 cbe=gbe*vbe;
                 gben = -c2/vbe;
@@ -256,9 +257,9 @@ int BJTdSetup(GENmodel *inModel, CKTcircuit *ckt)
             vtn=vt*here->BJTtemissionCoeffR;
             if(vbc > -5*vtn) {
                 evbc=exp(vbc/vtn);
-                cbc=csat*(evbc-1)+ckt->CKTgmin*vbc;
-                gbc=csat*evbc/vtn+ckt->CKTgmin;
-                gbc2=csat*evbc/vtn/vtn;
+                cbc=csatbc*(evbc-1)+ckt->CKTgmin*vbc;
+                gbc=csatbc*evbc/vtn+ckt->CKTgmin;
+                gbc2=csatbc*evbc/vtn/vtn;
                 gbc3=gbc2/vtn;
                 if (c4 == 0) {
                     cbcn=0;
@@ -272,7 +273,7 @@ int BJTdSetup(GENmodel *inModel, CKTcircuit *ckt)
                     gbcn3=gbcn2/vtc;
                 }
             } else {
-                gbc = -csat/vbc+ckt->CKTgmin;
+                gbc = -csatbc/vbc+ckt->CKTgmin;
                 gbc2=gbc3=0;
                 cbc = gbc*vbc;
                 gbcn = -c4/vbc;

src/spicelib/devices/bjt/bjtload.c

@@ -53,7 +53,7 @@ BJTload(GENmodel *inModel, CKTcircuit *ckt)
     double geqsub;
     double ceqsub;
     double cex;
-    double csat;
+    double csatbe, csatbc;
     double csubsat;
     double ctot;
     double czbc;
@@ -172,7 +172,8 @@ BJTload(GENmodel *inModel, CKTcircuit *ckt)
             /*
              *   dc model paramters
              */
-            csat=here->BJTtSatCur*here->BJTarea;
+            csatbe=here->BJTBEtSatCur*here->BJTarea;
+            csatbc=here->BJTBCtSatCur*here->BJTarea;
             csubsat=here->BJTtSubSatCur*here->BJTarea;
             rbpr=here->BJTtminBaseResist/here->BJTarea;
             rbpi=here->BJTtbaseResist/here->BJTarea-rbpr;
@@ -451,13 +452,13 @@ next1:      vtn=vt*here->BJTtemissionCoeffF;
 
             if(vbe >= -3*vtn){
                 evbe=exp(vbe/vtn);
-                cbe=csat*(evbe-1);
-                gbe=csat*evbe/vtn;
+                cbe=csatbe*(evbe-1);
+                gbe=csatbe*evbe/vtn;
             } else {
                 arg=3*vtn/(vbe*CONSTe);
                 arg = arg * arg * arg;
-                cbe = -csat*(1+arg);
-                gbe = csat*3*arg/vbe;
+                cbe = -csatbe*(1+arg);
+                gbe = csatbe*3*arg/vbe;
             }
             if (c2 == 0) {
                 cben=0;
@@ -481,13 +482,13 @@ next1:      vtn=vt*here->BJTtemissionCoeffF;
 
             if(vbc >= -3*vtn) {
                 evbc=exp(vbc/vtn);
-                cbc=csat*(evbc-1);
-                gbc=csat*evbc/vtn;
+                cbc=csatbc*(evbc-1);
+                gbc=csatbc*evbc/vtn;
             } else {
                 arg=3*vtn/(vbc*CONSTe);
                 arg = arg * arg * arg;
-                cbc = -csat*(1+arg);
-                gbc = csat*3*arg/vbc;
+                cbc = -csatbc*(1+arg);
+                gbc = csatbc*3*arg/vbc;
             }
             if (c4 == 0) {
                 cbcn=0;

src/spicelib/devices/bjt/bjtmask.c

@@ -42,6 +42,12 @@ BJTmAsk(CKTcircuit *ckt, GENmodel *instPtr, int which, IFvalue *value)
         case BJT_MOD_IS:
             value->rValue = here->BJTsatCur;
             return(OK);
+        case BJT_MOD_IBE:
+            value->rValue = here->BJTBEsatCur;
+            return(OK);
+        case BJT_MOD_IBC:
+            value->rValue = here->BJTBCsatCur;
+            return(OK);
         case BJT_MOD_BF:
             value->rValue = here->BJTbetaF;
             return(OK);

src/spicelib/devices/bjt/bjtmpar.c

@@ -46,6 +46,14 @@ BJTmParam(int param, IFvalue *value, GENmodel *inModel)
             mods->BJTsatCur = value->rValue;
             mods->BJTsatCurGiven = TRUE;
             break;
+        case BJT_MOD_IBE:
+            mods->BJTBEsatCur = value->rValue;
+            mods->BJTBEsatCurGiven = TRUE;
+            break;
+        case BJT_MOD_IBC:
+            mods->BJTBCsatCur = value->rValue;
+            mods->BJTBCsatCurGiven = TRUE;
+            break;
         case BJT_MOD_BF:
             mods->BJTbetaF = value->rValue;
             mods->BJTbetaFGiven = TRUE;

src/spicelib/devices/bjt/bjtsetup.c

@@ -47,6 +47,12 @@ BJTsetup(SMPmatrix *matrix, GENmodel *inModel, CKTcircuit *ckt, int *states)
         if(!model->BJTsatCurGiven) {
             model->BJTsatCur = 1e-16;
         }
+        if(!model->BJTBEsatCurGiven) {
+            model->BJTBEsatCur = model->BJTsatCur;
+        }
+        if(!model->BJTBCsatCurGiven) {
+            model->BJTBCsatCur = model->BJTsatCur;
+        }
         if(!model->BJTbetaFGiven) {
             model->BJTbetaF = 100;
         }
@@ -396,19 +402,6 @@ BJTsetup(SMPmatrix *matrix, GENmodel *inModel, CKTcircuit *ckt, int *states)
             model->BJTteMax = 1e99;
         }
 
-
-/*
- * COMPATABILITY WARNING!
- * special note:  for backward compatability to much older models, spice 2G
- * implemented a special case which checked if B-E leakage saturation
- * current was >1, then it was instead a the B-E leakage saturation current
- * divided by IS, and multiplied it by IS at this point.  This was not
- * handled correctly in the 2G code, and there is some question on its
- * reasonability, since it is also undocumented, so it has been left out
- * here.  It could easily be added with 1 line.  (The same applies to the B-C
- * leakage saturation current).   TQ  6/29/84
- */
-
         /* loop through all the instances of the model */
         for (here = BJTinstances(model); here != NULL ;
                 here=BJTnextInstance(here)) {

src/spicelib/devices/bjt/bjttemp.c

@@ -146,6 +146,14 @@ BJTtemp(GENmodel *inModel, CKTcircuit *ckt)
             if ((model->BJTtlev == 0) || (model->BJTtlev == 1)) {
                 factor = exp(factlog);
                 here->BJTtSatCur = model->BJTsatCur * factor;
+                if (model->BJTBEsatCurGiven) {
+                    factor = exp(factlog / model->BJTemissionCoeffF);
+                    here->BJTBEtSatCur = model->BJTBEsatCur * factor;
+                }
+                if (model->BJTBCsatCurGiven) {
+                    factor = exp(factlog / model->BJTemissionCoeffR);
+                    here->BJTBCtSatCur = model->BJTBCsatCur * factor;
+                }
                 if (model->BJTsubSatCurGiven)
                     here->BJTtSubSatCur = model->BJTsubSatCur * factor;
             } else if (model->BJTtlev == 3) {