From 98b84695bf4382ec09c95a0d9d5e5be93bce0a1e Mon Sep 17 00:00:00 2001
From: Holger Vogt <holger.vogt@uni-due.de>
Date: Fri, 20 Feb 2026 15:18:47 +0100
Subject: [PATCH] Prepare for instance parameter 'dtemp', required by
 commercial PDKs. Not yet support in the model, silently ignored.

---
 src/spicelib/devices/bsim4v6/b4v6.c       | 2 +-
 src/spicelib/devices/bsim4v6/b4v6ask.c    | 3 +++
 src/spicelib/devices/bsim4v6/b4v6par.c    | 4 ++++
 src/spicelib/devices/bsim4v6/b4v6set.c    | 3 ++-
 src/spicelib/devices/bsim4v6/bsim4v6def.h | 3 +++
 5 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/spicelib/devices/bsim4v6/b4v6.c b/src/spicelib/devices/bsim4v6/b4v6.c
index 1ecb91625..ee160010d 100644
--- a/src/spicelib/devices/bsim4v6/b4v6.c
+++ b/src/spicelib/devices/bsim4v6/b4v6.c
@@ -55,7 +55,7 @@ IOPR( "delvt0", BSIM4v6_DELVTO,  IF_REAL   , "Zero bias threshold voltage variat
 IOP( "mulu0", BSIM4v6_MULU0, IF_REAL, "Low field mobility multiplier"),
 IOP( "xgw",  BSIM4v6_XGW, IF_REAL, "Distance from gate contact center to device edge"),
 IOP( "ngcon", BSIM4v6_NGCON, IF_REAL, "Number of gate contacts"),
-
+IOPU("dtemp", BSIM4v6_DTEMP, IF_REAL,    "Instance temperature difference"),
 
 IOP( "trnqsmod", BSIM4v6_TRNQSMOD, IF_INTEGER, "Transient NQS model selector"),
 IOP( "acnqsmod", BSIM4v6_ACNQSMOD, IF_INTEGER, "AC NQS model selector"),
diff --git a/src/spicelib/devices/bsim4v6/b4v6ask.c b/src/spicelib/devices/bsim4v6/b4v6ask.c
index 64ce8b7bc..d9a025f0e 100644
--- a/src/spicelib/devices/bsim4v6/b4v6ask.c
+++ b/src/spicelib/devices/bsim4v6/b4v6ask.c
@@ -114,6 +114,9 @@ BSIM4v6instance *here = (BSIM4v6instance*)inst;
         case BSIM4v6_MULU0:
             value->rValue = here->BSIM4v6mulu0;
             return(OK);
+        case BSIM4v6_DTEMP:
+            value->rValue = here->BSIM4v6dtemp;
+            return(OK);
         case BSIM4v6_XGW:
             value->rValue = here->BSIM4v6xgw;
             return(OK);
diff --git a/src/spicelib/devices/bsim4v6/b4v6par.c b/src/spicelib/devices/bsim4v6/b4v6par.c
index 795fdc77c..f9430ab78 100644
--- a/src/spicelib/devices/bsim4v6/b4v6par.c
+++ b/src/spicelib/devices/bsim4v6/b4v6par.c
@@ -141,6 +141,10 @@ IFvalue *select)
             here->BSIM4v6mulu0 = value->rValue;
             here->BSIM4v6mulu0Given = TRUE;
             break;
+        case BSIM4v6_DTEMP:
+            here->BSIM4v6dtemp = value->rValue;
+            here->BSIM4v6dtempGiven = TRUE;
+            return(OK);
         case BSIM4v6_XGW:
             here->BSIM4v6xgw = value->rValue;
             here->BSIM4v6xgwGiven = TRUE;
diff --git a/src/spicelib/devices/bsim4v6/b4v6set.c b/src/spicelib/devices/bsim4v6/b4v6set.c
index 4ad739c34..3bf919304 100644
--- a/src/spicelib/devices/bsim4v6/b4v6set.c
+++ b/src/spicelib/devices/bsim4v6/b4v6set.c
@@ -2105,8 +2105,9 @@ BSIM4v6instance **InstArray;
                 here->BSIM4v6xgw = model->BSIM4v6xgw;
             if (!here->BSIM4v6ngconGiven)
                 here->BSIM4v6ngcon = model->BSIM4v6ngcon;
+            if (!here->BSIM4v6dtempGiven)
+                here->BSIM4v6dtemp = 0;
 
-                    
             /* Process instance model selectors, some
              * may override their global counterparts
 	     */
diff --git a/src/spicelib/devices/bsim4v6/bsim4v6def.h b/src/spicelib/devices/bsim4v6/bsim4v6def.h
index 94ee3b0c0..28f2aba35 100644
--- a/src/spicelib/devices/bsim4v6/bsim4v6def.h
+++ b/src/spicelib/devices/bsim4v6/bsim4v6def.h
@@ -114,6 +114,7 @@ typedef struct sBSIM4v6instance
     double BSIM4v6mulu0;
     double BSIM4v6xgw;
     double BSIM4v6ngcon;
+    double BSIM4v6dtemp;
 
      /* added here to account stress effect instance dependence */
     double BSIM4v6u0temp;
@@ -297,6 +298,7 @@ typedef struct sBSIM4v6instance
     unsigned BSIM4v6mulu0Given   :1;
     unsigned BSIM4v6xgwGiven   :1;
     unsigned BSIM4v6ngconGiven   :1;
+    unsigned BSIM4v6dtempGiven : 1;
     unsigned BSIM4v6icVDSGiven :1;
     unsigned BSIM4v6icVGSGiven :1;
     unsigned BSIM4v6icVBSGiven :1;
@@ -2713,6 +2715,7 @@ typedef struct sBSIM4v6model
 #define BSIM4v6_SC                  37
 #define BSIM4v6_M                   38
 #define BSIM4v6_MULU0               39
+#define BSIM4v6_DTEMP               40
 
 /* Global parameters */
 #define BSIM4v6_MOD_TEMPEOT         65