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+// Example 11.20: (a) AVF
+//                (b) AIF
+//                (c) RIF
+//                (d) ROF
+clc, clear
+btao=50;
+r_pi=1.1e3; // in ohms
+function[c]=parallel(a,b)
+    c=a*b/(a+b);
+endfunction
+// From equivalent circuit of amplifier without feedback in Fig. 11.60
+RS=4.7e3; // in ohms
+RF=15e3; // in ohms
+RE2=0.1e3; // in ohms
+RB1=parallel(91e3,10e3); // in ohms
+RC1=4.7e3; // in ohms
+RC2=4.7e3; // in ohms
+RB2=RB1; // in ohms
+
+disp("Part (b)");
+RL1=parallel(RS,parallel(RF+RE2,RB1)); // in ohms
+I1_IS=RL1/(RL1+r_pi); // I1/IS
+IC1_IS=btao*I1_IS; // IC1/IS
+Ri2=r_pi+(1+btao)*parallel(RE2,RF); // in ohms
+I2_IS=-IC1_IS*parallel(RC1,RB2)/(parallel(RC1,RB2)+Ri2); // in ohms
+IC2_IS=btao*I2_IS; // IC2/IS
+AID=-IC2_IS/2; // Open loop
+IF_IS=IC2_IS*RE2/(RE2+RF); // IF/IS
+bta=IF_IS/AID; // Feedback factor
+T=-bta*AID;
+AIF=AID/(1+T);
+disp(AIF,"AIF =");
+
+disp("Part (a)");
+AVF=AIF*RC2/RS;
+disp(AVF,"AVF =");
+
+disp("Part (c)");
+RID=parallel(parallel(RS,RE2+RF),parallel(RB1,r_pi)); // in ohms
+RIF=RID/(1+T); // in ohms
+disp(RIF,"RIF (Ω) =");
+
+disp("Part (d)");
+ROF=RC2*1e-3; // in kilo-ohms
+disp(ROF,"ROF (kΩ) =");
+\ No newline at end of file