600 Practical MATLAB® Applications for Engineers
g. Repeat H(f) versus f
∠H(w) versus f
H(f)dB versus f (semilog scale)
∠H(f ) versus f (semilog scale)
using standard circuit techniques.
ANALYTICAL Solution
Part (a)
Hw Vw
Vw
jwC
jwC
R
RC
jw
RC
o
i
() ()
()
*
* *
1
1
1
1
Part (b)
Hw RC
w
RC
()
1
2 1 2
*
*
∠H(w) = tan−^1 (w * R * C)
MATLAB Solution
% Script File: LP _ filter _ analysis
R=1e3/(2*pi);
C=.1e-6;
a=1/(R*C);
w =-5*a:10000:5*a;
num=a;
den=[1 a];
Hlp = freqs(num,den,w);
figure(1);
subplot(2,1,1);
plot(w/(2*pi),abs(Hlp));
xlabel (‘frequency in Hrz’);
ylabel (‘magnitude’);
title(‘Magnitude of H(f) vs. frequency’);
FIGURE 6.25
Circuit diagram of Example 6.1.
R = 1/(2*π) KΩ
Vi(w) C = 1 μF Vo(w)