MATLAB: Designing BPFs using butter function

band pass filterbpf

How do I design the following BPFs using butter function

Best Answer

As the frequency response of the Butterworth filter is maximally flat (no ripples), you do not have an option to specify the passband ripple and stopband attenuation values in butter function. In designfilt, you can specify the passband ripple and stopband attenuation values, however, they are not accepted for butterworth filter. You can use designfilt to design a butterworth bandpass filter as shown below.

d = designfilt('bandpassiir', 'FilterOrder', 20, 'HalfPowerFrequency1', 0.4, 'HalfPowerFrequency2', 0.6, 'DesignMethod', 'butter');
fvtool(d)

For more information, refer the following link

https://www.mathworks.com/help/signal/ref/designfilt.html

Related Solutions

MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

Déjà vu

how to design IIR highpass filter with cutoff frequency of 20Hz and FIR bandpass filter with cutoff frequency of 10Hz and 15Hz?

Make the appropriate changes to get the cascaded filter you want.

MATLAB: Fir and iir filtering

You have to know your filter specifications. If you do, you can do both with fdesign.lowpass and fdesign.highpass

fdesign.lowpass and fdesign.highpass have different specification strings which support different filter designs.

The default string 'Fp,Fst,Ap,Ast' supports both FIR and IIR designs.

Here is an example:

Design a lowpass filter with a passband frequency of 1 kHz, a stopband frequency of 1.5 kHz, passband ripple of 0.5 dB, and stopband attenuation of 40 dB. The sampling frequency is 20 kHz

   d = fdesign.lowpass('Fp,Fst,Ap,Ast',1e3,1.5e3,0.5,40,20e3);
   designmethods(d)  %shows which designs are valid for this spec
   Hdeq = design(d,'equiripple'); % FIR filter
   Hbutt = design(d,'butter'); %IIR design

Best Answer

Related Solutions

MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

MATLAB: Fir and iir filtering

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