Question

The circuit above has the following parameters: 

R=55 Ohm, C=1.5 uF ("u"=micro), L1=3 mH, L2=4 mH; 

Using MATLAB (or equivalent tool) generate the transfer function H = Vo/Vi magnitude MdB(f) and Phase(f) frequency dependencies in the frequency range from 100 Hz to 12000 Hz. 

Define the Magntude plot of the transfer function by entering f (Hz) and M (dB) points. Do not enter units.

Define the Phase plot of the transfer function by entering f (Hz) and Phase (in degrees) points. Do not enter units.

Answer 1

Script:1

syms s;

L1=0.003;L2=0.004;

C=1.5*(10^(-6));

R=55;

Z=[(1/s*C)+(s*L1) -s*L1 ;

-s*L1 (s*(L1+L2))+R ];

V=[1 0]';

I=inv(Z)*V;

H=I(2)*R

Command window:

H =

______________________________________________________________________________

Script 2:(From the above trasnfer function)

clc;close all;clear all;

b =[24349702177296608133120000 0 0];

a=[12174851088648304375000 1549526502191602375 24349702177296608133120000 1770887431076116955136];

f=linspace(100,12000,1000);

w=2*pi*f;

H=freqs(b,a,w);

figure;

subplot(211)

plot(f,20*log10(abs(H)));grid;

xlabel('f(Hz)');ylabel('|H|')

title('Magnitude response')

subplot(212)

plot(f,rad2deg(angle(H)));grid;

xlabel('f(Hz)');ylabel('')

title('Phase response')

%For tabulation

f=[100 200 400 600 800 1000 2000 4000 6000 8000];

w=2*pi*f;

H=freqs(b,a,w);

M=20*log10(abs(H));

PH=rad2deg(angle(H));

A=[f' M' PH']

f(Hz)     M(Mag) PH(phase)

103 ×

0.1000 0.0101 -0.0900
0.2000 0.0040 -0.0900
0.4000 -0.0020 -0.0900
0.6000 -0.0055 -0.0900
0.8000 -0.0080 -0.0900
1.0000 -0.0099 -0.0900
2.0000 -0.0160 -0.0900
4.0000 -0.0220 -0.0900
6.0000 -0.0255 -0.0900
8.0000 -0.0280 -0.0900