moscap.m

cmos仿真程序, cmos仿真程序, cmos仿真程序,

function cap = moscap(W, L, vgs, vds, vsb, tech, ctech)
% analysis of capacitances of MOS transistors;
% the function returns a vector of the type [cgs cgd cgb cdb csb]

% ctech is a vector of capacitor technology parameters [tox, cov, cj, mj, pb, cjsw, mjsw, pbsw]
% technology is a list of transistor technology parameters [type vt0 gamma beta lambda vdsat ld wd]

weff = (W - tech(8))*1.e-6;
leff = (L - tech(7))*1.e-6;
type = tech(1); % type is 1 for nmos, -1 for pmos

% drain and source junction capacitances
% it is assumed that the drain and source areas extend over 2.5 * L
sdarea = weff * L * 2.5 * 1.e-6;
sdperim = weff + 5 * L * 1.e-6;
cjdb = junctioncap(-(vds+vsb)*type, ctech(3), ctech(4), ctech(5))*sdarea;
cjswdb = junctioncap(-(vds+vsb)*type, ctech(6), ctech(7), ctech(8))*sdperim;
cdb = cjdb + cjswdb;
cjsb = junctioncap(-vsb*type, ctech(3), ctech(4), ctech(5))*sdarea;
cjswsb = junctioncap(-vsb*type, ctech(6), ctech(7), ctech(8))*sdperim;
csb = cjsb + cjswsb;

% gate capacitance
% determine first the operation region

vt = threshold(vsb, tech(1), tech(2), tech(3));

if (abs(vgs) < abs(vt))
   region = 0;
elseif (abs(vds) < abs(vgs - vt))
      region = 1;
else
   region = 2;
end;
gc = gatecap(weff, leff, ctech, region);

% create output vector
%cap = [gc(1) gc(2) gc(3) cdb csb];
cap = gc(1) +gc(2) +gc(3) +cdb +csb;