610
Practical MATLAB
® Applications for Engineers
FIGURE 6.37
Circuit diagram of Example 6.3.
V i (s)
V o (s)
C = 1F
L = 1H
R = 1 Ω
The solutions of Example 6.3 are given by the script fi le shifting_LPF as follows:
ANALYTICAL Solution
H s
R
sC
R
sC
sL
R
sC
R
sC
( ) ϭ
ϩ
ϩ
ϩ
1
1
1
1
H s
V s
V s
R
sC
R
sC
s L
R
sC
o
i
( )
( )
( )
ϭ
ϭ
ϩ
ϩ
1

 

 
H s
V s
V s
R
sC
sRL
R
sC
L
C
o
i
( )
( )
( )
ϭ
ϭ
ϩ
ϩ
H s
V s
V s
R
sC sRL
R
sC
L
C
o
i
( )
( )
( )
ϭ
ϭ
ϩ
ϩ

 

 
H s
V s
V s
R
s RLC Ls R
o
i
( )
( )
( )
ϭ
ϭ
ϩ ϩ
ϭ ϭ ϭ
2
for
1
R C L
H s
V s
V s
s
s
o
i
( )
( )
( )
ϭ
ϭ
ϩ ϩ
1
1
2
MATLAB Solution
% Script file: shifting _ LPF
% part(b), LPF with w n =1,R=L=C=1
num1=1;
den1= [1 1 1];
w = [0:.2:4];
H1 = freqs(num1,den1,w);
CRC_47760_CH006.indd 610
CRC_47760_CH006.indd 610
7/23/2008 2:26:45 PM
7/23/2008 2:26:45 PM