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diff --git a/339/CH7/EX7.4/ex7_4.sce b/339/CH7/EX7.4/ex7_4.sce
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+//first we define all parameters for the transistor and the circuit
+Z0=50; //characteristic imedance of the system
+
+Vcc=3.6; //power supply voltage
+Vce=2; //collector voltage 
+Ic=10e-3; //collector current
+
+T=300; //ambient temperature (300K)
+
+//transistor parameters (they are very similar to BFG403W)
+beta=145;    // current gain
+Is=5.5e-18;  // saturation current
+VAN= 30;     // forward Early voltage
+tau_f=4e-12; // forward transition time
+rb=125;      // base resistance
+rc=15;       // collector resistance
+re=1.5;      // emitter resistance
+Lb=1.1e-9;   // base inductance
+Lc=1.1e-9;   // collector inductance
+Le=0.5e-9;   // emitter inductance
+Cjc=16e-15;  // collector junction capacitance at zero applied voltage
+mc=0.2;      // collector junction grading coefficient
+Cje=37e-15;  // emitter junction capacitance at zero applied voltage
+me=0.35;     // emitter junction grading coefficient
+phi_be=0.9;  // base-emitter diffusion potential
+phi_bc=0.6;  // base-collector diffusion potential
+Vbe=phi_be;  // base-emitter voltage
+
+// some physical constants
+k=1.38e-23;   // Boltzmann's constant
+q=1.6e-19;    // elementary charge
+VT=k*T/q;     // thermal potential
+
+disp('DC biasing parameters');
+
+Ib=Ic/beta;
+disp("Amperes",Ib,"Base current");
+
+Rc=(Vcc-Vce)/Ic;
+disp("Ohms",Rc,"Collector resistance");
+
+Rb=(Vcc-Vbe)/Ib;
+disp("Ohms",Rb,"Base resistance");
+
+
+r_pi=VT/Ib;
+disp("Ohms",r_pi,"Rpi");
+
+r0=VAN/Ic;
+disp("Ohms",r0,"R0");
+
+gm=beta/r_pi;
+disp("Mho",gm,"Gm");
+
+Vbc=Vbe-Vce;
+Cmu=Cjc*(1-Vbc/phi_bc)^(-mc);
+disp("Farads",Cmu,"base collector capacitance");
+
+if(Vbe<0.5*phi_be)
+   Cpi_junct=Cje*(1-Vbe/phi_be)^(-me);
+else
+   C_middle=Cje*0.5^(-me);
+   k_middle=1-0.5*me;
+   Cpi_junct=C_middle*(k_middle+me*Vbe/phi_be);
+end;
+
+disp("Farads",Cpi_junct,"Junction Capacitance");
+
+Cpi_diff=Is*tau_f/VT*exp(Vbe/VT);
+disp("Farads",Cpi_diff,"Differential capacitance");
+
+Cpi=Cpi_junct+Cpi_diff;
+disp("Farads",Cpi,"Total Capacitance");
+
+C_miller=Cmu*(1+gm*r_pi/(r_pi+rb)*Z0*r0/(r0+rc+Z0));
+disp("Farads",C_miller,"Miller Capacitance");
+
+C_input=Cpi+C_miller;
+disp("Farads",C_input,"Total input capacitance");
+\ No newline at end of file