From 3c0fab2bfb7a5e41a54ebaf7aa637618054334c3 Mon Sep 17 00:00:00 2001
From: sjborley <sjborley>
Date: Mon, 23 May 2005 20:30:43 +0000
Subject: [PATCH] Fixed a divide-by-zero bug in the MOS level=2 device model.
 The fix was supplied by Hitoshi Tanaka.

---
 src/spicelib/devices/mos2/mos2dset.c | 3 +++
 src/spicelib/devices/mos2/mos2load.c | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/src/spicelib/devices/mos2/mos2dset.c b/src/spicelib/devices/mos2/mos2dset.c
index a3034779e..941563e02 100644
--- a/src/spicelib/devices/mos2/mos2dset.c
+++ b/src/spicelib/devices/mos2/mos2dset.c
@@ -2,6 +2,7 @@
 Copyright 1990 Regents of the University of California.  All rights reserved.
 Author: 1988 Jaijeet S Roychowdhury
 Modified: 2000 AlansFixes
+$Id$
 **********/
 
 #include "ngspice.h"
@@ -367,6 +368,8 @@ d_p.d3_pqr = 0.0;
 	    InvDeriv(&d_dbrgdb,&d_barg);
 	    TimesDeriv(&d_dbrgdb,&d_dbrgdb,-0.5);
 	} else {
+	    sphi = sqrt(here->MOS2tPhi); /* added by HT 050523 */
+	    sphi3 = here->MOS2tPhi*sphi; /* added by HT 050523 */
 	    barg = sphi/(1.0+0.5*(lvbs-lvds)/here->MOS2tPhi);
 	    EqualDeriv(&d_barg,&d_q); d_barg.value = lvbs - lvds;
 	    d_barg.d1_r -= 1.0;
diff --git a/src/spicelib/devices/mos2/mos2load.c b/src/spicelib/devices/mos2/mos2load.c
index 67c1d3f4a..b7bde6d81 100644
--- a/src/spicelib/devices/mos2/mos2load.c
+++ b/src/spicelib/devices/mos2/mos2load.c
@@ -2,6 +2,7 @@
 Copyright 1990 Regents of the University of California.  All rights reserved.
 Author: 1985 Thomas L. Quarles
 Modified: 2000 alansFixes
+$Id$
 **********/
 
 #include "ngspice.h"
@@ -584,6 +585,8 @@ next1:      if(vbs <= -3*vt) {
                 dbrgdb = -0.5/barg;
                 d2bdb2 = 0.5*dbrgdb/(phiMinVbs+lvds);
             } else {
+                sphi = sqrt(here->MOS2tPhi);/* added by HT 050523 */
+                sphi3 = here->MOS2tPhi*sphi;/* added by HT 050523 */
                 barg = sphi/(1.0+0.5*(lvbs-lvds)/here->MOS2tPhi);
                 tmp = barg/sphi3;
                 dbrgdb = -0.5*barg*tmp;
@@ -829,6 +832,8 @@ line500:
                     bsarg = sqrt(vdsat+phiMinVbs);
                     dbsrdb = -0.5/bsarg;
                 } else {
+					sphi = sqrt(here->MOS2tPhi);/* added by HT 050523 */
+					sphi3 = here->MOS2tPhi*sphi;/* added by HT 050523 */
                     bsarg = sphi/(1.0+0.5*(lvbs-vdsat)/here->MOS2tPhi);
                     dbsrdb = -0.5*bsarg*bsarg/sphi3;
                 }