path: root/testsuite/vests/vhdl-ams/ad-hoc/fromUC/simultaneous_stmts/test145.ams

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-- ---------------------------------------------------------------------
--
-- $Id: test145.ams,v 1.1 2002-03-27 22:11:19 paw Exp $
-- $Revision: 1.1 $
--
-- ---------------------------------------------------------------------

----------------------------------------------------------------------
-- SIERRA REGRESSION TESTING MODEL
-- Develooped at:
-- Distriburted Processing Laboratory
-- University of cincinnati
-- Cincinnati
----------------------------------------------------------------------
-- File          : test145.ams
-- Author(s)     : Geeta Balarkishnan(gbalakri@ececs.uc.edu)
-- Created       : June 2001
----------------------------------------------------------------------
-- Description :
--this is a mos model. It tests for the correctness of the procedural
--statement.
--
--the model accepts the mos data as generic constants. The terminals
--are defined as of nature electrical.
--it also tests the alias declaration for real'low.
--Charges associated with the 4 terminals are declared as quantities.
--The voltage associated with each of them is also defined.
--a signal is used to drive i.e to carry out a generic initialization.
--The various mos equations are evaluated depending on the conditions.
--The equations for charges and currents are evaluated.
----------------------------------------------------------------------

package mosdata is 
  NATURE electrical is real across real through;
  FUNCTION SIN(X : real) RETURN real;
  FUNCTION EXP(X : real) RETURN real;
  FUNCTION SQRT(X : real) RETURN real;
  FUNCTION POW(X,Y : real) RETURN real;
  alias undefined is real'low; 
  constant Temperature: real:=27.0;
  constant eps0 : real :=8.85418e-12; 
  constant Ni : real :=1.45e16; 
  constant Boltzmann : real :=1.380662e-23; 
  constant echarge: real :=1.6021892e-19; 
  constant epsSiO2 : real :=3.9*eps0; 
  constant epsSi : real :=11.7*eps0; 
  constant kTQ : real :=Boltzmann*temperature/echarge; 
  constant pi: real := 3.14159;  
end package mosdata; 

use work.mosdata.all; 
entity mos is 

  generic( 
    width  : real:=1.0E-4; 
    length : real:=1.0E-4;  
    channel: real :=1.0;
    kp :real:= 2.0E-5; 
    gamma :undefined; 
    phi   :undefined; 
    tox   :real:= 1.0E-7;
    nsub  :real:= 0.0;
    nss   :real:=0.0; 
    nfs   :real:= 0.0; 
    tpg   :real:= 1.0; 
    xj    :real:=0.0; 
    ld    :real:= 0.0; 
    u0    :real:= 600.0; 
    vmax  :real:=0.0;
    xqc   :real:= 1.0; 
    kf    :real:=0.0; 
    af    :real:=1.0; 
    fc    :real:=0.5; 
    delta :real:=0.0; 
    theta :real:=0.0; 
    eta   :real:=0.0;
    Sigma :real:=0.0;
    kappa :real:=0.2 );

  port ( terminal  drain,  gate,  source,  bulk  : electrical); 

end entity mos; 

architecture amos of mos is 
  quantity Qc, Qb, Qg: real;
  quantity Qcq, Qbq, Qgq : real; -- channel, bulk and gate charges 
  quantity Vdsq across drain to source; 
  quantity Vgsq across gate to source; 
  quantity Vbsq across bulk to source; 
  quantity Idq through drain; 
  quantity Igq through gate; 
  quantity Isq through source; 
  quantity Ibq through bulk; 

  signal Initialized: boolean; -- use a signal as generic initialisation 

begin 
  MOSeqns: procedural is 
     variable 
	cox,vt,beta,sigma,nsub,Phi,Gamma,nss,ngate,A,B,C,D,Vfb,fshort, 
        wp,wc,sqwpxj,vbulk,delv,vth,Vgstos, Vgst, 
	Ueff,Tau,Vsat,Vpp,fdrain, 
        stfct,leff,xd,qnfscox,fn,dcrit,deltal,It,Ids,R,Vds,Vgs,Vbs, 
        forward ,egfet,fermig, mobdeg: real;
  begin -- procedural statements 

    if not Initialized then 
      if tox<=0.0 then 
        cox:=epsSiO2/1.0e-7; 
      else 
        cox:=epsSiO2/tox; 
      end if; 

      if kp = 0.0 then 
        beta:=cox*u0; 
      else 
        beta:=kp; 
      end if; 

     nsub := nsub * 1.0e6;  -- scale nsub to SI units 
  
      if (phi = undefined) then 
        if (nsub > 0.0) then
		if (0.1<2.0*KTQ*(nsub/Ni)) then 
          	Phi:=(2.0*kTQ*(nsub/Ni));
		else
		Phi:=0.1;
		end if; 
        else 
          Phi:=0.6; 
        end if; 
      else 
        Phi:=phi; 
      end if;
  
      if (gamma = undefined) then 
        if (nsub > 0.0) then 
          Gamma:=sqrt(2.0*epsSi*echarge*nsub)/cox; 
        else 
          Gamma:=0.0; 
        end if; 
      else 
        Gamma:=gamma; 
      end if;

      nss:=nss*1.0e4;              -- Scale to SI 
      ngate:=gamma*1.0e4;           -- Scale to SI 

      leff:=length-2.0*ld; 
      if leff>0.0 then 
        Sigma:= eta * 8.15e-22/(cox*leff*leff*leff); 
      else 
        Sigma:=0.0; 
      end if; 

      if nsub>0.0 then -- N.B. nsub was scaled, above. 
        xd:=sqrt(2.0*epsSi/(echarge*nsub)); 
      else 
        xd:=0.0; 
      end if; 

      if (nfs>0.0) and(cox>0.0) then 
        qnfscox:=echarge*nfs/cox; 
      else 
        qnfscox:=0.0; 
      end if; 

      if cox>0.0 then 
        fn:=delta*pi*epsSi*0.5/(cox*width); 
      else 
        fn:=delta*pi*epsSi*0.5*tox/epsSiO2; 
      end if; 

      --Scale beta and convert cox from Fm^-2 to F 
      beta:=beta*width/leff; 
      cox:=cox*width*leff; 

      Initialized <= true; 
    end if; -- not initialized 

    Vds:=channel*Vdsq; 
    if Vds>=0.0 then 
        Vgs:=channel* Vgsq; 
        Vbs:=channel* Vbsq; 
        forward:=1.0; 
    else 
        Vds:=-Vds; 
        Vgs:=channel* Vgsq; 
        Vbs:=channel* Vbsq; 
        forward:=-1.0; 
    end if; 

    if Vbs<=0.0 then 
        A:=Phi-Vbs; 
        D:=sqrt(A); 
    else 
        D:=2.0*sqrt(Phi)*Phi/(2.0*Phi+Vbs); 
        A:=D*D; 
    end if; 

    Vfb:=Vt-Gamma*sqrt(Phi)-Sigma*Vds; 
    if (xd=0.0) OR (xj=0.0) then 
        fshort:=1.0; 
    else 
        wp:=xd*D; 
        wc:=0.0631353*xj+0.8013292*wp-0.01110777*wp*wp/xj; 
        sqwpxj:=sqrt(1.0-(wp*wp/((wp+xj)*(wp+xj)))); 
        fshort:=1.0-((ld+wc)*sqwpxj-ld)/leff; 
    end if; 

    vbulk:=Gamma*fshort*D+fn*A; 
    if nfs=0.0 then 
        delv:=0.0; 
    else 
        delv:=kTQ*(1.0+qnfscox+vbulk*0.5/A); 
    end if; 

    vth:=Vfb+vbulk; 
    Vgstos:=Vgs-Vfb;

    if (vgs-vth > delv) then  
        Vgst:=Vgs-vth;
    else
        Vgst:= delv;
    end if;
 
    if (vgs>=vth) or (delv/=0.0) then 

      if (Vbs<=0.0) or (Phi /= 0.0) then 
          B:=0.5*Gamma/D+fn; 
      else 
          B:=fn; 
      end if; 

      mobdeg:=1.0/(1.0+theta*Vgst); 
   
      if (vmax /=0.0) then 
         Ueff:=u0*mobdeg; 
          Tau:=Ueff/Leff*vmax; 
      else 
          Tau:=0.0; 
      end if; 

      Vsat:=Vgst/(1.0+B); 
      Vsat:=Vsat*(1.0-0.5*Tau*Vsat); -- not quite the same as SPICE 
      if (vds<Vsat) then
	Vpp:=vds;
      else
	Vpp:= Vsat;
      end if;

      fdrain:=1.0/(1.0+Tau*Vpp); 
      if (Vgs<vth+delv) and (nfs>0.0) then 
        stfct:=exp((Vgs-vth-delv)/delv); 
      else 
          stfct:=1.0; 
      end if; 

      if Vds>=Vsat then 
        if (kappa>0.0) and (xd>0.0) then 

          if vmax=0.0 then 
              deltal:=sqrt(kappa*xd*xd*(Vds-Vsat)); 
          else 
              dcrit:=(xd*xd*vmax*0.5)/(Ueff*(1.0-fdrain)); 
              
	      deltal:=sqrt(kappa*xd*xd*(Vds-Vsat)+dcrit*dcrit)-dcrit; 
          end if; 

          if deltal<=0.5*Leff then 
              C:=Leff/(Leff-deltal); 
          else 
              C:=4.0*deltal/Leff; 
          end if; 

        else 
            C:=1.0; 
        end if; 

      else 
          C:=1.0; 
      end if; 

      It:=Vgst-Vpp*(1.0+B)*0.5; 
        Beta:=Beta*mobdeg; 
        Ids:=Beta*Vpp*It*C*fdrain*stfct; 
    else 
        -- Cutoff 
        Ids:=0.0; 
    end if; -- vgs >= vth 

    if Cox /= 0.0 then 
        --Charges 
      if Vgs<=vth then 
        if Gamma /= 0.0 then 
          if Vgstos < -A then 
                Qg:=Cox*(Vgstos+A); -- Accumulation 
          else 
                Qg:=0.5*Gamma*Cox*(sqrt(4.0*(Vgstos+A)+Gamma*Gamma-Gamma)); 
          end if ; -- vgstos <-A 
        else-- Gamma = 0.0 
            Qg:=0.0; 
        end if; -- gamma /= 0 
          Qb:=-Qg; 
          Qc:=0.0; 
      else 
          -- depletion mode: 
          R:=(1.0+B)*Vpp*Vpp/(12.0*It); 
          Qg:=Cox*(Vgstos-Vpp*0.5+R); 
          Qc:=-Cox*(Vgst+(1.0+B)*(R-Vpp*0.5)); 
          Qb:=-(Qc+Qg); 
      end if;

    else 
        Qg:=0.0; 
        Qc:=0.0; 
        Qb:=0.0; 
    end if; -- cox /= 0 

    -- equations for charges (in a procedural we have assignments to 
    --quantitites): 
      Qcq := Qc; 
      Qgq := Qg; 
      Qbq := Qb; 

    -- equations for currents: 
      Idq := channel*forward*Ids+channel*xqc*Qc'dot; 
      Igq := channel*Qg'dot; 
      Ibq := channel*Qb'dot; 
      Isq := -Idq - Igq - Ibq; 

  end procedural; 
end architecture amos;