From 9ed7a24a0e3926e191176585d48da177ad2af670 Mon Sep 17 00:00:00 2001
From: dwarning <dwarning>
Date: Sun, 28 Jan 2024 20:11:52 +0100
Subject: [PATCH] mos1...3: Beta in noise w/o channel length modulation

---
 src/spicelib/devices/mos1/mos1noi.c | 7 +++----
 src/spicelib/devices/mos2/mos2noi.c | 7 +++----
 src/spicelib/devices/mos3/mos3noi.c | 7 +++----
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/src/spicelib/devices/mos1/mos1noi.c b/src/spicelib/devices/mos1/mos1noi.c
index ec7801963..2c853c9a9 100644
--- a/src/spicelib/devices/mos1/mos1noi.c
+++ b/src/spicelib/devices/mos1/mos1noi.c
@@ -111,8 +111,6 @@ MOS1noise(int mode, int operation, GENmodel * genmodel, CKTcircuit * ckt,
                         vds = *(ckt->CKTstate0 + inst->MOS1vds);
                         vgs = *(ckt->CKTstate0 + inst->MOS1vgs);
                         vgd = vgs - vds;
-                        beta = inst->MOS1tTransconductance * inst->MOS1m *
-                                   inst->MOS1w/(inst->MOS1l - 2 * model->MOS1latDiff);
 
                         vgst=(inst->MOS1mode==1?vgs:vgd) - model->MOS1type*inst->MOS1von;
                         if (vgst > 0) {
@@ -124,8 +122,9 @@ MOS1noise(int mode, int operation, GENmodel * genmodel, CKTcircuit * ckt,
                                 alpha = 1.0 - (vds*inst->MOS1mode/(model->MOS1type*inst->MOS1vdsat));
                             }
                         }
-                        double betap = beta*(1.0+model->MOS1lambda*(vds*inst->MOS1mode));
-                        Sid = 2.0 / 3.0 * betap * vgst * (1.0+alpha+alpha*alpha) / (1.0+alpha) * model->MOS1gdsnoi;
+                        beta = inst->MOS1tTransconductance * inst->MOS1m *
+                                   inst->MOS1w/(inst->MOS1l - 2 * model->MOS1latDiff);
+                        Sid = 2.0 / 3.0 * beta * vgst * (1.0+alpha+alpha*alpha) / (1.0+alpha) * model->MOS1gdsnoi;
                     }
 
                     NevalSrc( & noizDens[MOS1IDNOIZ], & lnNdens[MOS1IDNOIZ],
diff --git a/src/spicelib/devices/mos2/mos2noi.c b/src/spicelib/devices/mos2/mos2noi.c
index fdbcc3dbc..c3e942adf 100644
--- a/src/spicelib/devices/mos2/mos2noi.c
+++ b/src/spicelib/devices/mos2/mos2noi.c
@@ -100,8 +100,6 @@ MOS2noise(int mode, int operation, GENmodel * genmodel, CKTcircuit * ckt,
                         vds = *(ckt->CKTstate0 + inst->MOS2vds);
                         vgs = *(ckt->CKTstate0 + inst->MOS2vgs);
                         vgd = vgs - vds;
-                        beta = inst->MOS2tTransconductance * inst->MOS2m *
-                                   inst->MOS2w/(inst->MOS2l - 2 * model->MOS2latDiff);
 
                         vgst=(inst->MOS2mode==1?vgs:vgd) - model->MOS2type*inst->MOS2von;
                         if (vgst > 0) {
@@ -113,8 +111,9 @@ MOS2noise(int mode, int operation, GENmodel * genmodel, CKTcircuit * ckt,
                                 alpha = 1.0 - (vds*inst->MOS2mode/(model->MOS2type*inst->MOS2vdsat));
                             }
                         }
-                        double betap = beta*(1.0+model->MOS2lambda*(vds*inst->MOS2mode));
-                        Sid = 2.0 / 3.0 * betap * vgst * (1.0+alpha+alpha*alpha) / (1.0+alpha) * model->MOS2gdsnoi;
+                        beta = inst->MOS2tTransconductance * inst->MOS2m *
+                                   inst->MOS2w/(inst->MOS2l - 2 * model->MOS2latDiff);
+                        Sid = 2.0 / 3.0 * beta * vgst * (1.0+alpha+alpha*alpha) / (1.0+alpha) * model->MOS2gdsnoi;
                     }
 
                     NevalSrc( & noizDens[MOS2IDNOIZ], & lnNdens[MOS2IDNOIZ],
diff --git a/src/spicelib/devices/mos3/mos3noi.c b/src/spicelib/devices/mos3/mos3noi.c
index 7caa11e47..3d7551184 100644
--- a/src/spicelib/devices/mos3/mos3noi.c
+++ b/src/spicelib/devices/mos3/mos3noi.c
@@ -100,8 +100,6 @@ MOS3noise(int mode, int operation, GENmodel * genmodel, CKTcircuit * ckt,
                         vds = *(ckt->CKTstate0 + inst->MOS3vds);
                         vgs = *(ckt->CKTstate0 + inst->MOS3vgs);
                         vgd = vgs - vds;
-                        beta = inst->MOS3tTransconductance * inst->MOS3m *
-                                   inst->MOS3w/(inst->MOS3l - 2 * model->MOS3latDiff);
 
                         vgst=(inst->MOS3mode==1?vgs:vgd) - model->MOS3type*inst->MOS3von;
                         if (vgst > 0) {
@@ -113,8 +111,9 @@ MOS3noise(int mode, int operation, GENmodel * genmodel, CKTcircuit * ckt,
                                 alpha = 1.0 - (vds*inst->MOS3mode/(model->MOS3type*inst->MOS3vdsat));
                             }
                         }
-                        double betap = beta;
-                        Sid = 2.0 / 3.0 * betap * vgst * (1.0+alpha+alpha*alpha) / (1.0+alpha) * model->MOS3gdsnoi;
+                        beta = inst->MOS3tTransconductance * inst->MOS3m *
+                                   inst->MOS3w/(inst->MOS3l - 2 * model->MOS3latDiff);
+                        Sid = 2.0 / 3.0 * beta * vgst * (1.0+alpha+alpha*alpha) / (1.0+alpha) * model->MOS3gdsnoi;
                     }
 
                     NevalSrc( & noizDens[MOS3IDNOIZ], & lnNdens[MOS3IDNOIZ],