From ecac7a07a2fa8f1f3284cce4387f334041edc526 Mon Sep 17 00:00:00 2001
From: dwarning <dwarning>
Date: Tue, 2 Sep 2025 11:15:38 +0200
Subject: [PATCH] bsim4: reimplement mobility and binning extension

---
 src/spicelib/devices/bsim4/b4.c       |  3 ++-
 src/spicelib/devices/bsim4/b4ask.c    |  6 ++++++
 src/spicelib/devices/bsim4/b4par.c    |  8 ++++++++
 src/spicelib/devices/bsim4/b4set.c    |  2 ++
 src/spicelib/devices/bsim4/b4temp.c   |  3 +++
 src/spicelib/devices/bsim4/bsim4def.h | 20 +++++++++++++-------
 6 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/src/spicelib/devices/bsim4/b4.c b/src/spicelib/devices/bsim4/b4.c
index d0fddd8b3..b39901f32 100644
--- a/src/spicelib/devices/bsim4/b4.c
+++ b/src/spicelib/devices/bsim4/b4.c
@@ -55,9 +55,10 @@ IOP( "rbps", BSIM4_RBPS,  IF_REAL   , "Body resistance"),
 IOP( "rbpd", BSIM4_RBPD,  IF_REAL   , "Body resistance"),
 IOP( "delvto", BSIM4_DELVTO,  IF_REAL   , "Zero bias threshold voltage variation"),
 IOPR("delvt0", BSIM4_DELVTO,  IF_REAL   , "Zero bias threshold voltage variation"),
+IOP( "mulu0", BSIM4_MULU0, IF_REAL, "Low field mobility multiplier"),
 IOP( "xgw",  BSIM4_XGW, IF_REAL, "Distance from gate contact center to device edge"),
 IOP( "ngcon", BSIM4_NGCON, IF_REAL, "Number of gate contacts"),
-
+IOP( "wnflag", BSIM4_WNFLAG, IF_INTEGER, "W/NF device flag for bin selection"),
 
 IOP( "trnqsmod", BSIM4_TRNQSMOD, IF_INTEGER, "Transient NQS model selector"),
 IOP( "acnqsmod", BSIM4_ACNQSMOD, IF_INTEGER, "AC NQS model selector"),
diff --git a/src/spicelib/devices/bsim4/b4ask.c b/src/spicelib/devices/bsim4/b4ask.c
index 76874bf73..c0f843e95 100644
--- a/src/spicelib/devices/bsim4/b4ask.c
+++ b/src/spicelib/devices/bsim4/b4ask.c
@@ -129,6 +129,12 @@ BSIM4instance *here = (BSIM4instance*)inst;
         case BSIM4_DELVTO:
             value->rValue = here->BSIM4delvto;
             return(OK);
+        case BSIM4_MULU0:
+            value->rValue = here->BSIM4mulu0;
+            return(OK);
+        case BSIM4_WNFLAG:
+            value->iValue = here->BSIM4wnflag;
+            return(OK);
         case BSIM4_XGW:
             value->rValue = here->BSIM4xgw;
             return(OK);
diff --git a/src/spicelib/devices/bsim4/b4par.c b/src/spicelib/devices/bsim4/b4par.c
index 1ecd4af88..ac4a274c5 100644
--- a/src/spicelib/devices/bsim4/b4par.c
+++ b/src/spicelib/devices/bsim4/b4par.c
@@ -157,6 +157,14 @@ IFvalue *select)
             here->BSIM4delvto = value->rValue;
             here->BSIM4delvtoGiven = TRUE;
             break;
+        case BSIM4_MULU0:
+            here->BSIM4mulu0 = value->rValue;
+            here->BSIM4mulu0Given = TRUE;
+            break;
+        case BSIM4_WNFLAG:
+            here->BSIM4wnflag = value->iValue;
+            here->BSIM4wnflagGiven = TRUE;
+            break;
         case BSIM4_XGW:
             here->BSIM4xgw = value->rValue;
             here->BSIM4xgwGiven = TRUE;
diff --git a/src/spicelib/devices/bsim4/b4set.c b/src/spicelib/devices/bsim4/b4set.c
index 05185af03..0637be32e 100644
--- a/src/spicelib/devices/bsim4/b4set.c
+++ b/src/spicelib/devices/bsim4/b4set.c
@@ -2354,6 +2354,8 @@ BSIM4instance **InstArray;
                 here->BSIM4rbpd = model->BSIM4rbpd;
             if (!here->BSIM4delvtoGiven)
                 here->BSIM4delvto = 0.0;
+            if (!here->BSIM4mulu0Given)
+                here->BSIM4mulu0 = 1.0;
             if (!here->BSIM4xgwGiven)
                 here->BSIM4xgw = model->BSIM4xgw;
             if (!here->BSIM4ngconGiven)
diff --git a/src/spicelib/devices/bsim4/b4temp.c b/src/spicelib/devices/bsim4/b4temp.c
index 172bb74ad..b9a0434c7 100644
--- a/src/spicelib/devices/bsim4/b4temp.c
+++ b/src/spicelib/devices/bsim4/b4temp.c
@@ -1768,6 +1768,9 @@ int Fatal_Flag = 0;
             here->BSIM4vth0 += here->BSIM4delvto;
             here->BSIM4vfb = pParam->BSIM4vfb + model->BSIM4type * here->BSIM4delvto;
 
+            /* low field mobility multiplier */
+            here->BSIM4u0temp = pParam->BSIM4u0temp * here->BSIM4mulu0;
+
         /* Instance variables calculation  */
             T3 = model->BSIM4type * here->BSIM4vth0
                - here->BSIM4vfb - pParam->BSIM4phi;
diff --git a/src/spicelib/devices/bsim4/bsim4def.h b/src/spicelib/devices/bsim4/bsim4def.h
index 59d82ceab..a2bff4121 100644
--- a/src/spicelib/devices/bsim4/bsim4def.h
+++ b/src/spicelib/devices/bsim4/bsim4def.h
@@ -117,6 +117,8 @@ typedef struct sBSIM4instance
     double BSIM4rbpd;
 
     double BSIM4delvto;
+    double BSIM4mulu0;
+    int BSIM4wnflag;
     double BSIM4xgw;
     double BSIM4ngcon;
 
@@ -310,6 +312,8 @@ typedef struct sBSIM4instance
     unsigned BSIM4rbpdGiven   :1;
     unsigned BSIM4rbpsGiven   :1;
     unsigned BSIM4delvtoGiven   :1;
+    unsigned BSIM4mulu0Given   :1;
+    unsigned BSIM4wnflagGiven   :1;
     unsigned BSIM4xgwGiven   :1;
     unsigned BSIM4ngconGiven   :1;
     unsigned BSIM4icVDSGiven :1;
@@ -2864,14 +2868,16 @@ typedef struct sBSIM4model
 #define BSIM4_SCC                 36
 #define BSIM4_SC                  37
 #define BSIM4_M                   38
+#define BSIM4_MULU0               39
+#define BSIM4_WNFLAG              40
 
-#define BSIM4_VGSTEFF             40
-#define BSIM4_VDSEFF              41
-#define BSIM4_CGSO                42
-#define BSIM4_CGDO                43
-#define BSIM4_CGBO                44
-#define BSIM4_WEFF                45
-#define BSIM4_LEFF                46
+#define BSIM4_VGSTEFF             41
+#define BSIM4_VDSEFF              42
+#define BSIM4_CGSO                43
+#define BSIM4_CGDO                44
+#define BSIM4_CGBO                45
+#define BSIM4_WEFF                46
+#define BSIM4_LEFF                47
 
 /* Global parameters */
 #define BSIM4_MOD_TEMPEOT         66