% Ouput voltage N-bit DAC with optimal resistors

N    = 4;
Vc   = 3.3;
Vmax = 0.7;
ZL   = 75;

b = 0:(N-1);
k = 0:(2^N-1);

% Optimal resistor values for linear ouput curve, you can change them to
% obtain other output curves.
% 
r = ZL*(2^N - 1)*(Vc/Vmax - 1) * 2.^(-b) + 0

 r(1) = 3.9e3;
 r(2) = 2.2e3;
 r(3) = 1.0e3;
 r(4) = 470;
% r(5) = r(5)*1.8;

out = zeros(1, length(k));

for i=1:length(k)
    
    % dec2binvec is in Data Acquisition Toolbox, but it's very easy to
    % write it if you don't have this toolbox installed.
    a      = dec2binvec(k(i), N);
    
    out(i) = DAC_out(Vc, ZL, r, a);
end

hold on

hb = plot(k, out,            '-db', 'DisplayName', 'REAL ');
hg = plot(k, k*Vmax/(2^N-1), '-sg', 'DisplayName', 'IDEAL');

legend('show');

title (sprintf('DAC N=%i-bit output voltage, V_c=%.2f, V_{max}=%.2f, Z_L=%i', N, Vc, Vmax, ZL));
ylabel('Vo (V)');
xlabel('Number to convert');

grid