Question

A bandpass series filter has parameter values of R=150Ω , C=2μF and
L=3mH . The filter is energized with a voltage source which has an
internal resistance equal to 100Ω.
Using Matlab, write a code to print Bode magnitude plots for the filter transfer function by
itself and the transfer function of the filter modified by the source resistance?

Answer 1

The circuit diagram of a bandpass series filter is shown below

Applying KVL

Taking Laplace Transform on both sides

So

The MATLAB code for obtaining the bode plot is

clc;
clear all;
close all;

s = tf('s');
G = 300e-6*s/(6e-9*s^2 +300e-6*s +1);
bode(G);
grid on;

The bode plot obtained is shown below

Case - II When the internal resistance is also considered

The transfer function will be changed to the following. The resistor value will be changed as the internal resistance comes in series .

The MATLAB code

clc;
clear all;
close all;

s = tf('s');
G = 500e-6*s/(6e-9*s^2 +500e-6*s +1);
bode(G);
grid on;

The plot