% given G1=1/(s+1), G2=1/s, G3=2 num1 = 1; den1 = [1 1]; sysG1 = tf(num1,den1); num2 = 1; den2 = [1 0]; sysG2 = tf(num2,den2); num3 = 2; den3 = 1; sysG3 = tf(num3,den3); % series connection sysG1G2 = sysG1*sysG2; % unit feedback numf = 1; denf = 1; sysF = tf(numf, denf); % or sysG1G2F = feedback(sysG1G2,sysF,-1); sysG1G2F = feedback(sysG1G2,sysF); % parallel connection [sysT] = parallel(sysG1G2F,sysG3)