add parallel resistor rds (between outer drain and source nodes, parallel to bulk diode)

src/spicelib/devices/vdmos/vdmos.c

@@ -97,6 +97,7 @@ IFparm VDMOSmPTable[] = { /* model parameters */
  IOP("bv",    VDMOS_MOD_BV,    IF_REAL,   "Vds breakdown voltage"),
  IOP("ibv",   VDMOS_MOD_IBV,   IF_REAL,   "Current at Vds=bv"),
  IOP("nbv",   VDMOS_MOD_NBV,   IF_REAL,   "Vds breakdown emission coefficient"),
+ IOP("rds",   VDMOS_MOD_RDS,   IF_REAL,   "Drain-source shunt resistance"),
  IOP("rb",    VDMOS_MOD_RB,    IF_REAL,   "Body diode ohmic resistance"),
  IOP("n",     VDMOS_MOD_N,     IF_REAL,   "Bulk diode emission coefficient"),
  IOP("tt",    VDMOS_MOD_TT,    IF_REAL,   "Body diode transit time"),

src/spicelib/devices/vdmos/vdmosdefs.h

@@ -54,6 +54,7 @@ typedef struct sVDMOSinstance {
     double VDMOSsourceConductance;   /*conductance of source(or 0):set in setup*/
     double VDMOSdrainConductance;    /*conductance of drain(or 0):set in setup*/
     double VDMOSgateConductance;    /*conductance of gate(or 0):set in setup*/
+    double VDMOSdsConductance;    /*conductance of drain to source:set in setup*/
     double VDMOStemp;    /* operating temperature of this instance */
     double VDMOSdtemp;   /* operating temperature of the instance relative to circuit temperature*/
 
@@ -245,6 +246,10 @@ typedef struct sVDMOSinstance {
                              * (gate node, gate prime node) */
     double *VDMOSGPgPtr;    /* pointer to sparse matrix element at
                              * (gate prime node, gate node) */
+    double *VDMOSDsPtr;    /* pointer to sparse matrix element at
+                             * (source node, drain node) */
+    double *VDMOSSdPtr;    /* pointer to sparse matrix element at
+                             * (drain node, source node) */
     /* bulk diode */
     double *VDIORPdPtr;    /* pointer to sparse matrix element at
                              * (diode prime node, drain node) */
@@ -340,6 +345,7 @@ typedef struct sVDMOSmodel {       /* model structure for a resistor */
     double VDIOresistTemp1;
     double VDIOresistTemp2;
     double VDIOconductance;
+    double VDMOSrds;
     double VDMOSDn;
     double VDIOtransitTime;
     double VDIOtranTimeTemp1;
@@ -377,6 +383,7 @@ typedef struct sVDMOSmodel {       /* model structure for a resistor */
     unsigned VDIOjunctionPotGiven :1;
     unsigned VDIObrkdEmissionCoeffGiven :1;
     unsigned VDIOresistanceGiven :1;
+    unsigned VDMOSrdsGiven   :1;
     unsigned VDMOSDnGiven   :1;
     unsigned VDIOtransitTimeGiven :1;
     unsigned VDMOSDegGiven   :1;
@@ -437,6 +444,7 @@ enum {
     VDMOS_MOD_BV,
     VDMOS_MOD_IBV,
     VDMOS_MOD_NBV,
+    VDMOS_MOD_RDS,
     VDMOS_MOD_N,
     VDMOS_MOD_TT,
     VDMOS_MOD_EG,

src/spicelib/devices/vdmos/vdmosload.c

@@ -563,9 +563,6 @@ bypass :
                 ceqgb = ceqgb - gcgb*vgb + ckt->CKTag[0] *
                         *(ckt->CKTstate0 + here->VDMOSqgb);
             }
-            /*
-             *     store charge storage info for meyer's cap in lx table
-             */
 
             /*
              *  load current vector
@@ -597,9 +594,9 @@ bypass :
              *  load y matrix
              */
 
-            *(here->VDMOSDdPtr) += (here->VDMOSdrainConductance);
+            *(here->VDMOSDdPtr) += (here->VDMOSdrainConductance + here->VDMOSdsConductance);
             *(here->VDMOSGgPtr) += (here->VDMOSgateConductance); //((gcgd + gcgs + gcgb));
-            *(here->VDMOSSsPtr) += (here->VDMOSsourceConductance);
+            *(here->VDMOSSsPtr) += (here->VDMOSsourceConductance + here->VDMOSdsConductance);
             *(here->VDMOSBbPtr) += (here->VDMOSgbd + here->VDMOSgbs + gcgb);
             *(here->VDMOSDPdpPtr) +=
                 (here->VDMOSdrainConductance + here->VDMOSgds +
@@ -630,6 +627,9 @@ bypass :
             *(here->VDMOSSPdpPtr) += (-here->VDMOSgds - xrev*
                                       (here->VDMOSgm + here->VDMOSgmbs));
 
+            *(here->VDMOSDsPtr) += (-here->VDMOSdsConductance);
+            *(here->VDMOSSdPtr) += (-here->VDMOSdsConductance);
+
 
             /* bulk diode model
              * Delivers reverse conduction and forward breakdown

src/spicelib/devices/vdmos/vdmosmask.c

@@ -95,6 +95,9 @@ VDMOSmAsk(CKTcircuit *ckt, GENmodel *inst, int which, IFvalue *value)
         case VDMOS_MOD_NBV:
             value->rValue = model->VDIObrkdEmissionCoeff;
             return(OK);
+        case VDMOS_MOD_RDS:
+            value->rValue = model->VDMOSrds;
+            return(OK);
         case VDMOS_MOD_FC:
             value->rValue = model->VDIOdepletionCapCoeff;
             return(OK);

src/spicelib/devices/vdmos/vdmosmpar.c

@@ -133,6 +133,10 @@ VDMOSmParam(int param, IFvalue *value, GENmodel *inModel)
             model->VDIObrkdEmissionCoeff = value->rValue;
             model->VDIObrkdEmissionCoeffGiven = TRUE;
             break;
+        case VDMOS_MOD_RDS:
+            model->VDMOSrds = value->rValue;
+            model->VDMOSrdsGiven = TRUE;
+            break;
         case VDMOS_MOD_N:
             model->VDMOSDn = value->rValue;
             model->VDMOSDnGiven = TRUE;

src/spicelib/devices/vdmos/vdmosset.c

@@ -84,6 +84,9 @@ VDMOSsetup(SMPmatrix *matrix, GENmodel *inModel, CKTcircuit *ckt,
         if (!model->VDIObrkdEmissionCoeffGiven) {
             model->VDIObrkdEmissionCoeff = 1.;
         }
+        if (!model->VDMOSrdsGiven) {
+            model->VDMOSrds = 1.0e30;
+        }
         if (!model->VDMOSDnGiven) {
             model->VDMOSDn = 1.;
         }
@@ -279,6 +282,9 @@ do { if((here->ptr = SMPmakeElt(matrix, here->first, here->second)) == NULL){\
             TSTALLOC(VDMOSGgpPtr, VDMOSgNode, VDMOSgNodePrime);
             TSTALLOC(VDMOSGPgPtr, VDMOSgNodePrime, VDMOSgNode);
 
+            TSTALLOC(VDMOSDsPtr, VDMOSdNode, VDMOSsNode);
+            TSTALLOC(VDMOSSdPtr, VDMOSsNode, VDMOSdNode);
+
             TSTALLOC(VDIORPdPtr, VDIOposPrimeNode, VDMOSdNode);
             TSTALLOC(VDIODrpPtr, VDMOSdNode, VDIOposPrimeNode);
             TSTALLOC(VDIOSrpPtr, VDMOSsNode, VDIOposPrimeNode);

src/spicelib/devices/vdmos/vdmostemp.c

@@ -160,6 +160,18 @@ VDMOStemp(GENmodel *inModel, CKTcircuit *ckt)
             } else {
                 here->VDMOSgateConductance = 0;
             }
+            if (model->VDMOSrdsGiven) {
+                if (model->VDMOSrds != 0) {
+                    here->VDMOSdsConductance = here->VDMOSm /
+                        model->VDMOSrds;
+                }
+                else {
+                    here->VDMOSdsConductance = 0;
+                }
+            }
+            else {
+                here->VDMOSdsConductance = 0;
+            }
 
             /* bulk diode model */
             double egfet1, arg1, fact1, pbfact1, pbo, gmaold;