How can i Assign the value of cut-off frequency ?

f=[0.01:0.01:2e04];
s=2*pi*f;
wc1=j*2*pi*10;
wc2=j*2*pi*500;
H1=(s+wc1).^-1;
H2=(s.^2+(wc1+wc2)*s+wc1*wc2).^-1;
MH1=abs(H1);
MH2=abs(H2);
semilogx(f,20*log10(MH1/max(MH1)),'r')
hold on
semilogx(f,20*log10(MH2/max(MH2)),'k')

Answer 1

[Chunru]

f=[0.01:0.01:2e04];
s=2*pi*f;
wc1=j*2*pi*10;   % fc
wc2=j*2*pi*500;
H1=(s+wc1).^-1;
H2=(s.^2+(wc1+wc2)*s+wc1*wc2).^-1;
MH1=abs(H1);
MH2=abs(H2);
semilogx(f,20*log10(MH1/max(MH1)),'r')
hold on
semilogx(f,20*log10(MH2/max(MH2)),'k')
yline(-3);  % -3dB
xline(10);
grid on

[3lewwi]

thanks bro if you can i have another question say : Find the slops of the rejected band curves.

[Chunru]

The slope for H1 is roughly 20dB/decative.

The slope for H2 is varying with frequency. Between 10 and 500Hz, the slope for H2 is roughly 20dB/decative. Beyond 500Hz, the slope is roughly 40dB/decative.

[3lewwi]

big thanks broo