mos3load.c

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                here->MOS3gbd = DrainSatCur*evbd/vt + ckt->CKTgmin;
                here->MOS3cbd = DrainSatCur*(evbd-1) + ckt->CKTgmin*vbd;
            }

            /* now to determine whether the user was able to correctly
             * identify the source and drain of his device
             */
            if(vds >= 0) {
                /* normal mode */
                here->MOS3mode = 1;
            } else {
                /* inverse mode */
                here->MOS3mode = -1;
            }

            {
		/*
		 * subroutine moseq3(vds,vbs,vgs,gm,gds,gmbs,
		 * qg,qc,qb,cggb,cgdb,cgsb,cbgb,cbdb,cbsb)
		 */

		/* this routine evaluates the drain current, its
		 * derivatives and the charges associated with the
		 * gate, channel and bulk for mosfets based on
		 * semi-empirical equations */

		double coeff0 = 0.0631353e0;
		double coeff1 = 0.8013292e0;
		double coeff2 = -0.01110777e0;
		double oneoverxl;   /* 1/effective length */
		double eta; /* eta from model after length factor */
		double phibs;   /* phi - vbs */
		double sqphbs;  /* square root of phibs */
		double dsqdvb;  /*  */
		double sqphis;  /* square root of phi */
		double sqphs3;  /* square root of phi cubed */
		double wps;
		double oneoverxj;   /* 1/junction depth */
		double xjonxl;  /* junction depth/effective length */
		double djonxj;
		double wponxj;
		double arga;
		double argb;
		double argc;
		double dwpdvb;
		double dadvb;
		double dbdvb;
		double gammas;
		double fbodys;
		double fbody;
		double onfbdy;
		double qbonco;
		double vbix;
		double wconxj;
		double dfsdvb;
		double dfbdvb;
		double dqbdvb;
		double vth;
		double dvtdvb;
		double csonco;
		double cdonco;
		double dxndvb = 0.0;
		double dvodvb = 0.0;
		double dvodvd = 0.0;
		double vgsx;
		double dvtdvd;
		double onfg;
		double fgate;
		double us;
		double dfgdvg;
		double dfgdvd;
		double dfgdvb;
		double dvsdvg;
		double dvsdvb;
		double dvsdvd;
		double xn = 0.0;
		double vdsc;
		double onvdsc = 0.0;
		double dvsdga;
		double vdsx;
		double dcodvb;
		double cdnorm;
		double cdo;
		double cd1;
		double fdrain = 0.0;
		double fd2;
		double dfddvg = 0.0;
		double dfddvb = 0.0;
		double dfddvd = 0.0;
		double gdsat;
		double cdsat;
		double gdoncd;
		double gdonfd;
		double gdonfg;
		double dgdvg;
		double dgdvd;
		double dgdvb;
		double emax;
		double emongd;
		double demdvg;
		double demdvd;
		double demdvb;
		double delxl;
		double dldvd;
		double dldem;
		double ddldvg;
		double ddldvd;
		double ddldvb;
		double dlonxl;
		double xlfact;
		double diddl;
		double gds0 = 0.0;
		double emoncd;
		double ondvt;
		double onxn;
		double wfact;
		double gms;
		double gmw;
		double fshort;
		    
		/*
		 *     bypasses the computation of charges
		 */
		    
		/*
		 *     reference cdrain equations to source and
		 *     charge equations to bulk
		 */
		vdsat = 0.0;
		oneoverxl = 1.0/EffectiveLength;
		eta = model->MOS3eta * 8.15e-22/(model->MOS3oxideCapFactor*
						 EffectiveLength*EffectiveLength*EffectiveLength);
		/*
		 *.....square root term
		 */
		if ( (here->MOS3mode==1?vbs:vbd) <=  0.0 ) {
		    phibs  =  here->MOS3tPhi-(here->MOS3mode==1?vbs:vbd);
		    sqphbs  =  sqrt(phibs);
		    dsqdvb  =  -0.5/sqphbs;
		} else {
		    sqphis = sqrt(here->MOS3tPhi);
		    sqphs3 = here->MOS3tPhi*sqphis;
		    sqphbs = sqphis/(1.0+(here->MOS3mode==1?vbs:vbd)/
				     (here->MOS3tPhi+here->MOS3tPhi));
		    phibs = sqphbs*sqphbs;
		    dsqdvb = -phibs/(sqphs3+sqphs3);
		}
		/*
		 *.....short channel effect factor
		 */
		if ( (model->MOS3junctionDepth != 0.0) && 
		     (model->MOS3coeffDepLayWidth != 0.0) ) {
		    wps = model->MOS3coeffDepLayWidth*sqphbs;
		    oneoverxj = 1.0/model->MOS3junctionDepth;
		    xjonxl = model->MOS3junctionDepth*oneoverxl;
		    djonxj = model->MOS3latDiff*oneoverxj;
		    wponxj = wps*oneoverxj;
		    wconxj = coeff0+coeff1*wponxj+coeff2*wponxj*wponxj;
		    arga = wconxj+djonxj;
		    argc = wponxj/(1.0+wponxj);
		    argb = sqrt(1.0-argc*argc);
		    fshort = 1.0-xjonxl*(arga*argb-djonxj);
		    dwpdvb = model->MOS3coeffDepLayWidth*dsqdvb;
		    dadvb = (coeff1+coeff2*(wponxj+wponxj))*dwpdvb*oneoverxj;
		    dbdvb = -argc*argc*(1.0-argc)*dwpdvb/(argb*wps);
		    dfsdvb = -xjonxl*(dadvb*argb+arga*dbdvb);
		} else {
		    fshort = 1.0;
		    dfsdvb = 0.0;
		}
		/*
		 *.....body effect
		 */
		gammas = model->MOS3gamma*fshort;
		fbodys = 0.5*gammas/(sqphbs+sqphbs);
		fbody = fbodys+model->MOS3narrowFactor/EffectiveWidth;
		onfbdy = 1.0/(1.0+fbody);
		dfbdvb = -fbodys*dsqdvb/sqphbs+fbodys*dfsdvb/fshort;
		qbonco =gammas*sqphbs+model->MOS3narrowFactor*phibs/EffectiveWidth;
		dqbdvb = gammas*dsqdvb+model->MOS3gamma*dfsdvb*sqphbs-
		    model->MOS3narrowFactor/EffectiveWidth;
		/*
		 *.....static feedback effect
		 */
		vbix = here->MOS3tVbi*model->MOS3type-eta*(here->MOS3mode*vds);
		/*
		 *.....threshold voltage
		 */
		vth = vbix+qbonco;
		dvtdvd = -eta;
		dvtdvb = dqbdvb;
		/*
		 *.....joint weak inversion and strong inversion
		 */
		von = vth;
		if ( model->MOS3fastSurfaceStateDensity != 0.0 ) {
		    csonco = CHARGE*model->MOS3fastSurfaceStateDensity * 
			1e4 /*(cm**2/m**2)*/ *EffectiveLength*EffectiveWidth *
			here->MOS3m/OxideCap;
		    cdonco = qbonco/(phibs+phibs);
		    xn = 1.0+csonco+cdonco;
		    von = vth+vt*xn;
		    dxndvb = dqbdvb/(phibs+phibs)-qbonco*dsqdvb/(phibs*sqphbs);
		    dvodvd = dvtdvd;
		    dvodvb = dvtdvb+vt*dxndvb;
		} else {
		    /*
		     *.....cutoff region
		     */
		    if ( (here->MOS3mode==1?vgs:vgd) <= von ) {
			cdrain = 0.0;
			here->MOS3gm = 0.0;
			here->MOS3gds = 0.0;
			here->MOS3gmbs = 0.0;
			goto innerline1000;
		    }
		}
		/*
		 *.....device is on
		 */
		vgsx = MAX((here->MOS3mode==1?vgs:vgd),von);
		/*
		 *.....mobility modulation by gate voltage
		 */
		onfg = 1.0+model->MOS3theta*(vgsx-vth);
		fgate = 1.0/onfg;
		us = here->MOS3tSurfMob * 1e-4 /*(m**2/cm**2)*/ *fgate;
		dfgdvg = -model->MOS3theta*fgate*fgate;
		dfgdvd = -dfgdvg*dvtdvd;
		dfgdvb = -dfgdvg*dvtdvb;
		/*
		 *.....saturation voltage
		 */
		vdsat = (vgsx-vth)*onfbdy;
		if ( model->MOS3maxDriftVel <= 0.0 ) {
		    dvsdvg = onfbdy;
		    dvsdvd = -dvsdvg*dvtdvd;
		    dvsdvb = -dvsdvg*dvtdvb-vdsat*dfbdvb*onfbdy;
		} else {
		    vdsc = EffectiveLength*model->MOS3maxDriftVel/us;
		    onvdsc = 1.0/vdsc;
		    arga = (vgsx-vth)*onfbdy;
		    argb = sqrt(arga*arga+vdsc*vdsc);
		    vdsat = arga+vdsc-argb;
		    dvsdga = (1.0-arga/argb)*onfbdy;
		    dvsdvg = dvsdga-(1.0-vdsc/argb)*vdsc*dfgdvg*onfg;
		    dvsdvd = -dvsdvg*dvtdvd;
		    dvsdvb = -dvsdvg*dvtdvb-arga*dvsdga*dfbdvb;
		}
		/*
		 *.....current factors in linear region
		 */
		vdsx = MIN((here->MOS3mode*vds),vdsat);
		if ( vdsx == 0.0 ) goto line900;
		cdo = vgsx-vth-0.5*(1.0+fbody)*vdsx;
		dcodvb = -dvtdvb-0.5*dfbdvb*vdsx;
		/* 
		 *.....normalized drain current
		 */
		cdnorm = cdo*vdsx;
		here->MOS3gm = vdsx;
		if ((here->MOS3mode*vds) > vdsat) here->MOS3gds = -dvtdvd*vdsx;
		else here->MOS3gds = vgsx-vth-(1.0+fbody+dvtdvd)*vdsx;
		here->MOS3gmbs = dcodvb*vdsx;
		/* 
		 *.....drain current without velocity saturation effect
		 */
		cd1 = Beta*cdnorm;
		Beta = Beta*fgate;
		cdrain = Beta*cdnorm;
		here->MOS3gm = Beta*here->MOS3gm+dfgdvg*cd1;
		here->MOS3gds = Beta*here->MOS3gds+dfgdvd*cd1;
		here->MOS3gmbs = Beta*here->MOS3gmbs+dfgdvb*cd1;
		/*
		 *.....velocity saturation factor
		 */
		if ( model->MOS3maxDriftVel > 0.0 ) {
		    fdrain = 1.0/(1.0+vdsx*onvdsc);
		    fd2 = fdrain*fdrain;
		    arga = fd2*vdsx*onvdsc*onfg;
		    dfddvg = -dfgdvg*arga;
		    if ((here->MOS3mode*vds) > vdsat) dfddvd = -dfgdvd*arga;
		    else dfddvd = -dfgdvd*arga-fd2*onvdsc;
		    dfddvb = -dfgdvb*arga;
		    /*
		     *.....drain current
		     */
		    here->MOS3gm = fdrain*here->MOS3gm+dfddvg*cdrain;
		    here->MOS3gds = fdrain*here->MOS3gds+dfddvd*cdrain;
		    here->MOS3gmbs = fdrain*here->MOS3gmbs+dfddvb*cdrain;
		    cdrain = fdrain*cdrain;
		    Beta = Beta*fdrain;
		}
		/*
		 *.....channel length modulation
		 */
		    
		if ( (here->MOS3mode*vds) <= vdsat ) {
		    if ( (model->MOS3maxDriftVel > 0.0) ||
			 (model->MOS3alpha == 0.0) ||
			 (ckt->CKTbadMos3)                    ) goto line700;
		    else {
			arga = (here->MOS3mode*vds)/vdsat;
			delxl = sqrt(model->MOS3kappa*model->MOS3alpha*vdsat/8);
			dldvd = 4*delxl*arga*arga*arga/vdsat;
			arga *= arga;
			arga *= arga;
			delxl *= arga;
			ddldvg = 0.0;
			ddldvd = -dldvd;
			ddldvb = 0.0;
			goto line520;
		    };
		};
			    
		if ( model->MOS3maxDriftVel <= 0.0 ) goto line510;
		if (model->MOS3alpha == 0.0) goto line700;
		cdsat = cdrain;
		gdsat = cdsat*(1.0-fdrain)*onvdsc;
		gdsat = MAX(1.0e-12,gdsat);
		gdoncd = gdsat/cdsat;
		gdonfd = gdsat/(1.0-fdrain);
		gdonfg = gdsat*onfg;
		dgdvg = gdoncd*here->MOS3gm-gdonfd*dfddvg+gdonfg*dfgdvg;
		dgdvd = gdoncd*here->MOS3gds-gdonfd*dfddvd+gdonfg*dfgdvd;
		dgdvb = gdoncd*here->MOS3gmbs-gdonfd*dfddvb+gdonfg*dfgdvb;
			    
		if (ckt->CKTbadMos3)
			emax = cdsat*oneoverxl/gdsat;
		else
			emax = model->MOS3kappa * cdsat*oneoverxl/gdsat;
		emoncd = emax/cdsat;
		emongd = emax/gdsat;
		demdvg = emoncd*here->MOS3gm-emongd*dgdvg;
		demdvd = emoncd*here->MOS3gds-emongd*dgdvd;
		demdvb = emoncd*here->MOS3gmbs-emongd*dgdvb;
			    
		arga = 0.5*emax*model->MOS3alpha;
		argc = model->MOS3kappa*model->MOS3alpha;
		argb = sqrt(arga*arga+argc*((here->MOS3mode*vds)-vdsat));
		delxl = argb-arga;
		if (argb != 0.0) {
			dldvd = argc/(argb+argb);
			dldem = 0.5*(arga/argb-1.0)*model->MOS3alpha;
		} else {
			dldvd = 0.0;
			dldem = 0.0;
		}
		ddldvg = dldem*demdvg;
		ddldvd = dldem*demdvd-dldvd;
		ddldvb = dldem*demdvb;
		goto line520;
line510:
		if (ckt->CKTbadMos3) {
		  delxl = sqrt(model->MOS3kappa*((here->MOS3mode*vds)-vdsat)*
				     model->MOS3alpha);
		  dldvd = 0.5*delxl/((here->MOS3mode*vds)-vdsat);
	       	} else {
		  delxl = sqrt(model->MOS3kappa*model->MOS3alpha*
				     ((here->MOS3mode*vds)-vdsat+(vdsat/8)));
		  dldvd =  0.5*delxl/((here->MOS3mode*vds)-vdsat+(vdsat/8));
	        };
		ddldvg = 0.0;
		ddldvd = -dldvd;
		ddldvb = 0.0;
		/*
		 *.....punch through approximation
		 */
line520:
		if ( delxl > (0.5*EffectiveLength) ) {
		delxl = EffectiveLength-(EffectiveLength*EffectiveLength/
						 (4.0*delxl));
		arga = 4.0*(EffectiveLength-delxl)*(EffectiveLength-delxl)/
			    (EffectiveLength*EffectiveLength);
		ddldvg = ddldvg*arga;
		ddldvd = ddldvd*arga;
		ddldvb = ddldvb*arga;
		dldvd =  dldvd*arga;
		}
		/*
		 *.....saturation region
		 */
		dlonxl = delxl*oneoverxl;
		xlfact = 1.0/(1.0-dlonxl);

		cd1 = cdrain;
		cdrain = cdrain*xlfact;
		diddl = cdrain/(EffectiveLength-delxl);
		here->MOS3gm = here->MOS3gm*xlfact+diddl*ddldvg;
		here->MOS3gmbs = here->MOS3gmbs*xlfact+diddl*ddldvb;
		gds0 = diddl*ddldvd;
		here->MOS3gm = here->MOS3gm+gds0*dvsdvg;
		here->MOS3gmbs = here->MOS3gmbs+gds0*dvsdvb;
		here->MOS3gds = here->MOS3gds*xlfact+diddl*dldvd+gds0*dvsdvd;
/*              here->MOS3gds = (here->MOS3gds*xlfact)+gds0*dvsdvd-
	           (cd1*ddldvd/(EffectiveLength*(1-2*dlonxl+dlonxl*dlonxl)));*/
			    
		/*
		 *.....finish strong inversion case
		 */
line700:
		if ( (here->MOS3mode==1?vgs:vgd) < von ) {
		/*
		 *.....weak inversion
		 */
		onxn = 1.0/xn;
		ondvt = onxn/vt;
		wfact = exp( ((here->MOS3mode==1?vgs:vgd)-von)*ondvt );
		cdrain = cdrain*wfact;
		gms = here->MOS3gm*wfact;
		gmw = cdrain*ondvt;
		here->MOS3gm = gmw;
		if ((here->MOS3mode*vds) > vdsat) {
		    here->MOS3gm = here->MOS3gm+gds0*dvsdvg*wfact;
		}
		here->MOS3gds = here->MOS3gds*wfact+(gms-gmw)*dvodvd;
		here->MOS3gmbs = here->MOS3gmbs*wfact+(gms-gmw)*dvodvb-gmw*
			    ((here->MOS3mode==1?vgs:vgd)-von)*onxn*dxndvb;
		}
		/*
		 *.....charge computation
		 */
		goto innerline1000;
		/*
		 *.....special case of vds = 0.0d0
		 */
line900:
		Beta = Beta*fgate;
		cdrain = 0.0;