Plotting the bode plot of a high pass filter using matlab
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I am trying to theoretically find the frequency response of the circuit given below:
Firstly i found the impedance value of the RC Ladder by applying the equation below, then i defined this as "Z" in my MatLab Code.
Afterwards i wrote a matlab code to plot the filter's frequency response. Matlab Code is given below, the required nominal values shown in the schematic are defined in the code.
f = logspace(0, 5, 1000);
w=2*pi.*f;
s=1i.*w;
Ro=11960e3;
R1=2.17e3;
R2=118.44e3;
R3=496.82e3;
R4=1220e3;
R5=2530e3;
C1=536.29e-12;
C2=217.23e-12;
C3=201.41e-12;
C4=263.35e-12;
C5=556.27e-12;
Rload=200e3;
Z=((1/Ro)+(R1+(1./(s*C1)))+(R2+(1./(s*C2)))+(R3+(1./(s*C3)))+(R4+(1./(s*C4)))+(R5+(1./(s*C5)))).^-1;
H=abs(Rload./(Z+Rload));
semilogx(f, 20*log10(H))
The LTSpice plot (expected one) is like this:
My Matlab Plot is like this:
My mathematical approach seems correct to me let me know if i have anything missing on that part. I am unsure about the code, please let me know if there is something missing in code or my mathematical approach.
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Answers (1)
Star Strider
on 13 May 2024
The ‘H’ calculation may be reversed. (I can’t read the axis values on the LTSpice plot image.)
Perhaps this —
f = logspace(0, 5, 1000);
w=2*pi.*f;
s=1i.*w;
Ro=11960e3;
R1=2.17e3;
R2=118.44e3;
R3=496.82e3;
R4=1220e3;
R5=2530e3;
C1=536.29e-12;
C2=217.23e-12;
C3=201.41e-12;
C4=263.35e-12;
C5=556.27e-12;
Rload=200e3;
Z=((1/Ro)+(R1+(1./(s*C1)))+(R2+(1./(s*C2)))+(R3+(1./(s*C3)))+(R4+(1./(s*C4)))+(R5+(1./(s*C5)))).^-1;
H=abs(Z./(Z+Rload));
semilogx(f, 20*log10(H))
.
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