Analyze of 3. Order Passive RLC Low Pass Filter

Matrix Lab

 

YILDIZ TECHNICAL UNIVERSITY
Department of Mechatronics Engineering

Lecture :

MKT 2822 Electronics and Communication Circuits

 

 

ANALYZE of 3. ORDER PASSIVE RLC LOW PASS FILTER with MATLAB

3. Order passive RLC low pass filteri figure 1

Divided Two Circuit

First Order Low Pass Filter                                          Second Order Low Pass Filter

3. Order passive RLC low pass filteri figure 2

Transfer Function of First Order Low Pass Filter

R=49.9 ohm  C=8.2 pF

1. Order passive RC low pass filteri figure 3

Cutoff Frequency of First Order Low Pass Filter

Matlab Code of Bode Diagram

num=[2443912214.6732];

den=[1 2443912214.6732];

G=tf(num, den);

bode(G);

grid on;

title('First Order LPF Bode Diagram');

Bode Diagram of First Order Low Pas Filter with Matlab Figure

Bode Diagram of First Order Low Pas Filter with Matlab Figure 4

Transfer Funtion of Second Order Low Pass Filter

R=150 ohm  C=27pF  L=56nH

Second Order Passive Low Pass Filter figure 5

 

Cutoff Frequency of Second Order Low Pass Filter

Matlab Code of Bode Diagram

num=[6.6137566137566*1e17];

den=[1 246913580.24691 6.6137566137566*1e17];

G=tf(num, den);

bode(G);

grid on;

title('Second Order LPF Bode Diagram');

Bode Diagram of Second Order Low Pas Filter with Matlab Figure

Second Order Low Pas Filter figure 6

Transfer Function of Third Order Low Pass Filter

R1=49.9ohm  C1=8.2pF  L1=56nH  R2=150ohm  C2=27pF

 

3. Order passive RLC low pass filteri figure 7

Matlab Code of Bode Diagram

num=[2443912214.6732];

den=[1 2443912214.6732];

num2=[6.6137566137566*1e17];

den2=[1 246913580.24691 6.6137566137566*1e17];

G=tf(num, den);

H=tf(num2,den2);

T=G*H;

bode(T);

grid on;

title('Third Order Bode LPF Diagram');

Bode Diagram of Third Order Low Pas Filter with Matlab Figure

Third Order Low Pas Filter figure 8

Cutoff Frequency

When we look at second order (fig 6) and third order (fig 8) bode diagram graphs, we see that the cut off frequencies are same. As a result, we can say that the cut off frequency of total circuit depends on the second order cut off frequency for this case.

 

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