Find the phasor gain K=\mathrm{V}_{\mathrm{O}} / \mathrm{V}_{\mathrm{S}} and input impedance Z_{\mathrm{IN}} of the circuit in Figure P8-53.
Use node-voltage analysis to solve the problem.
clear all
syms Vs Va Vo
% Create the node-voltage equations
Eqn1 = (Va-Vs)/(-15e3j) + Va/20e3 + (Va-Vo)/(-25e3j);
Eqn2 = (Vo-Va)/(-25e3j) + (Vo-Vs)/10e3;
Soln = solve(Eqn1,Eqn2,Va,Vo);
Vo = Soln.Vo;
K = double(Vo/Vs)
MagK = abs(K)
PhaseK = angle(K)*180/pi
% Find the input current to compute the input impedance
Iin1 = (Vs-Vo)/10e3;
Va = Soln.Va;
Iin2 = (Vs-Va)/(-15e3j);
Iin = Iin1+Iin2;
Zin = double(simplify(Vs/Iin))
K =
847.2873e-003 - 28.1313e-003i
MagK =
847.7542e-003
PhaseK =
-1.9016e+000
Zin =
21.3235e+003 - 9.7059e+003i