--- /dev/null
+## Copyright (C) 2006-2009 Carlo de Falco, Massimiliano Culpo
+##
+## This file is part of:
+## OCS - A Circuit Simulator for Octave
+##
+## OCS is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program (see the file LICENSE); if not,
+## see <http://www.gnu.org/licenses/>.
+##
+## author: Carlo de Falco <cdf _AT_ users.sourceforge.net>, culpo@math.uni-wuppertal.de
+
+## -*- texinfo -*-
+##
+## @deftypefn{Function File} @
+## {[@var{a},@var{b},@var{c}]=} Mshichmanhodgesmosfet(@var{string},@var{parameters},@
+## @var{parameternames},@var{extvar},@var{intvar},@var{t})
+##
+## SBN file implementing Schichman-Hodges MOSFETs model.
+##
+## @var{string} is used to select among models. Possible models are:
+##
+## @enumerate
+## @item @var{string} = "NMOS" (Schichman-Hodges n-MOSFET)
+## @item @var{string} = "PMOS" (Schichman-Hodges p-MOSFET)
+## @end enumerate
+##
+## Parameters for all the above models are:
+## @itemize
+## @item rd -> parasitic resistance between drain and source
+## @item W -> MOSFET width
+## @item L -> channel length
+## @item mu0 -> reference value for mobility
+## @item Vth -> threshold voltage
+## @item Cox -> oxide capacitance
+## @item Cgs -> gate-source capacitance
+## @item Cgd -> gate-drain capacitance
+## @item Cgb -> gate-bulk capacitance
+## @item Csb -> source-bulk capacitance
+## @item Cdb -> drain-bulk capacitance
+## @item Tshift -> shift for reference temperature on MOSFETs (default 0)
+## @end itemize
+##
+## See the @cite{IFF file format specifications} for details about
+## the output structures.
+##
+## @seealso{prs_iff,asm_initialize_system,asm_build_system}
+## @end deftypefn
+
+function [a,b,c]= Mshichmanhodgesmosfet (string,parameters,parameternames,extvar,intvar,t)
+
+ if isempty(intvar)
+ ## If intvar is empty, then we are initializing the system
+ ## and there is no need of a matrix evaluation
+ a = sparse(10,10);
+ b = [];
+ c = [];
+ else
+ ## If intvar is NOT empty, then we are evaluating the
+ ## element stamp
+ switch string
+ case "NMOS"
+
+ rd = 1e6;
+ W = 1;
+ L = 1;
+ mu0 = 1e-5;
+ Vth = .5;
+ Cox = 1e-9;
+ Cgb = Cox;
+ Cgs=Cgd=Csb=Cdb=.1*Cox;
+ Tshift = 0;
+
+ for ii=1:length(parameternames)
+ eval([parameternames{ii} "=",...
+ num2str(parameters(ii)) " ;"])
+ endfor
+
+ [gm,gd,ids,didT,P,dPdT,dPdvgs,dPdvds] = \
+ nmos(extvar,mu0,Cox,W,L,Vth,rd,Tshift);
+
+ vg = extvar(1);
+ vs = extvar(2);
+ vd = extvar(3);
+ vb = extvar(4);
+ T = max(extvar(5),0);
+
+ if isempty(intvar)
+ intvar = zeros(5,1);
+ endif
+
+ Qgb = intvar(1);
+ Qgs = intvar(2);
+ Qgd = intvar(3);
+ Qsb = intvar(4);
+ Qdb = intvar(5);
+
+ a11 = a21 = a22 = zeros(5,5);
+ a12 = [ 1 1 1 0 0; \
+ 0 -1 0 1 0; \
+ 0 0 -1 0 1; \
+ -1 0 0 -1 -1; \
+ 0 0 0 0 0];
+
+ a = [a11 a12; a21 a22];
+
+ b11 = [0 0 0 0 0; \
+ -gm (gm+gd) -gd 0 -didT; \
+ gm -(gm+gd) gd 0 didT; \
+ 0 0 0 0 0; \
+ dPdvgs -(dPdvgs+dPdvds) dPdvds 0 dPdT];
+
+ b12 = zeros(5,5);
+
+ b21 = [Cgb 0 0 -Cgb 0; \
+ Cgs -Cgs 0 0 0; \
+ Cgd 0 -Cgd 0 0; \
+ 0 Csb 0 -Csb 0; \
+ 0 0 Cdb -Cdb 0];
+ b22 = -eye(5);
+
+ b = [b11 b12; b21 b22];
+
+
+ c1 = [0; -ids; ids; 0; P];
+
+ c2 = [Cgb*(vg - vb) - Qgb;\
+ Cgs*(vg - vs) - Qgs;\
+ Cgd*(vg - vd) - Qgd;\
+ Csb*(vs - vb) - Qsb;\
+ Cdb*(vd - vb) - Qdb];
+
+ c = [c1;c2];
+
+
+ break;
+
+ case "PMOS"
+
+ rd = 1e6;
+ W = 1;
+ L = 1;
+ mu0 = 1e-5;
+ Vth = -.5;
+ Cox = 1e-9;
+ Cgb=Cox;
+ Cgs=Cgd=Csb=Cdb=.1*Cox;
+ Tshift = 0;
+
+ for ii=1:length(parameternames)
+ eval([parameternames{ii} "=",...
+ num2str(parameters(ii)) " ;"])
+ endfor
+
+ [gm,gd,ids,didT,P,dPdT,dPdvgs,dPdvds] = \
+ pmos(extvar,mu0,Cox,W,L,Vth,rd,Tshift);
+
+
+ vg = extvar(1);
+ vs = extvar(2);
+ vd = extvar(3);
+ vb = extvar(4);
+ T = extvar(5);
+
+ if isempty(intvar)
+ intvar = zeros(5,1);
+ endif
+
+ Qgb = intvar(1);
+ Qgs = intvar(2);
+ Qgd = intvar(3);
+ Qsb = intvar(4);
+ Qdb = intvar(5);
+
+ a11 = a21 = a22 = zeros(5,5);
+ a12 = [ 1 1 1 0 0; \
+ 0 -1 0 1 0; \
+ 0 0 -1 0 1; \
+ -1 0 0 -1 -1; \
+ 0 0 0 0 0];
+
+ a = [a11 a12; a21 a22];
+
+ b11 = [0 0 0 0 0; \
+ -gm (gm+gd) -gd 0 -didT; \
+ gm -(gm+gd) gd 0 didT; \
+ 0 0 0 0 0; \
+ dPdvgs -(dPdvgs+dPdvds) dPdvds 0 dPdT];
+
+ b12 = zeros(5,5);
+
+ b21 = [Cgb 0 0 -Cgb 0; \
+ Cgs -Cgs 0 0 0; \
+ Cgd 0 -Cgd 0 0; \
+ 0 Csb 0 -Csb 0; \
+ 0 0 Cdb -Cdb 0];
+
+ b22 = -eye(5);
+
+ b = [b11 b12; b21 b22];
+
+
+ c1 = [0; -ids; ids; 0; P];
+
+ c2 = [Cgb*(vg - vb) - Qgb;\
+ Cgs*(vg - vs) - Qgs;\
+ Cgd*(vg - vd) - Qgd;\
+ Csb*(vs - vb) - Qsb;\
+ Cdb*(vd - vb) - Qdb];
+
+ c = [c1;c2];
+
+ break;
+
+ otherwise
+ error(["unknown option:" string]);
+ endswitch
+ endif
+
+endfunction
+
+function [gm,gd,ids,didT,P,dPdT,dPdvgs,dPdvds] = nmos(extvar,mu0,Cox,W,L,Vth,rd,Tshift)
+ ##Computes values for nmos case
+
+ vg = extvar(1);
+ vs = extvar(2);
+ vd = extvar(3);
+ vb = extvar(4);
+ T = max(extvar(5),0);
+
+ k = mu0*Cox*((T + Tshift)/300)^(-3/2)*W/L;
+ dkdT = mu0*Cox*W*(-3/2)*((T + Tshift)/300)^(-5/2)*(1/300)/L;
+
+ vgs = vg-vs;
+ vds = vd-vs;
+
+ if (vgs < Vth)
+
+ gm = 0;
+ gd = 1/rd;
+ ids = vds*gd;
+ didT= 0;
+
+ elseif (((vgs-Vth) >= (vds)) && (vds >= 0))
+
+ ids = k*((vgs-Vth)*vds-(vds^2)/2)+vds/rd;
+ gm = k*vds;
+ gd = k*(vgs-Vth-vds) + 1/rd;
+ didT= dkdT*((vgs-Vth)*vds-(vds^2)/2);
+
+ elseif (((vgs-Vth) >= (vds)) && (vds < 0))
+
+ gm = 0;
+ gd = 1/rd;
+ ids = vds*gd;
+ didT= 0;
+
+ else # (i.e. if 0 <= vgs-vth <= vds)
+
+ ids = (k/2)*(vgs-Vth)^2+vds/rd;
+ gm = k*(vgs-Vth);
+ gd = 1/rd;
+ didT= (dkdT/(2))*(vgs-Vth)^2;
+
+ endif
+
+ P = -ids * vds;
+ dPdT = -didT* vds;
+ dPdvgs = -(gm*vds);
+ dPdvds = -(gd*vds + ids);
+
+endfunction
+
+function [gm,gd,ids,didT,P,dPdT,dPdvgs,dPdvds] = pmos(extvar,mu0,Cox,W,L,Vth,rd,Tshift)
+ ##Computes values for pmos case
+
+ vg = extvar(1);
+ vs = extvar(2);
+ vd = extvar(3);
+ vb = extvar(4);
+ T = extvar(5);
+
+ k = - mu0 * Cox * ((T + Tshift)/300)^(-3/2) *W/L;
+ dkdT = - mu0 * Cox * W *(-3/2)*((T + Tshift)/300)^(-5/2)*(1/300)/L;
+
+ vgs = vg-vs;
+ vds = vd-vs;
+
+ if (vgs > Vth)
+
+ gm = 0;
+ gd = 1/rd;
+ ids = vds*gd;
+ didT= 0;
+
+ elseif (((vgs-Vth) <= (vds)) && (vds <= 0))
+
+ ids = k*((vgs-Vth)*vds-(vds^2)/2)+vds/rd;
+ gm = k*vds;
+ gd = k*(vgs-Vth-vds)+1/rd;
+ didT= dkdT*((vgs-Vth)*vds-(vds^2)/2);
+
+ elseif (((vgs-Vth) <= (vds)) && (vds > 0))
+
+ gm = 0;
+ gd = 1/rd;
+ ids = vds*gd;
+ didT= 0;
+
+ else
+
+ ids = (k/2)*(vgs-Vth)^2+vds/rd;
+ gm = k*(vgs-Vth);
+ gd = 1/rd;
+ didT= (dkdT/(2))*(vgs-Vth)^2;
+
+ endif
+
+ P = -ids * vds;
+ dPdT = -didT* vds;
+ dPdvgs = -(gm*vds);
+ dPdvds = -(gd*vds + ids);
+
+endfunction
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