Butterworth Filter Design

In this experiment we designed a digital filter from analog filter. The input specifications that were given are passband attenuation, stopband attenuation, passband frequency, stopband frequency and sampling frequency. The passband and stopband attenuation values were given in dB and the passband stopband and sampling frequency were given in Hz. Using this data as input from the user we designed the low pass and high pass Butterworth filter. A lowpass filter is a filter that passes signals with a frequency lower than a certain cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency. A highpass filter is a filter that passes signals with a frequency higher than a cutoff frequency and attenuates signals with frequency lower than the cutoff frequency. The observed values of the passband and stopband attenuation were noted down and their waveforms were observed on Scilab. Analog LPF poles lie on the lefthand side of the s-plane hence the analog filter is stable. Also the digital LPF poles lie inside the unit circle hence the Digital LPF also is stable. Thus the magnitude spectrum is monotonic in both passband and stopband. In this way we performed this experiment.

Comments

  1. Vk25 April 2017 at 22:24

    well explained.

    ReplyDelete
  2. Unknown25 April 2017 at 22:39

    Very informative content.

    ReplyDelete
  3. Unknown25 April 2017 at 22:47

    We used BLT method for design of the filter.

    ReplyDelete
  4. Unknown28 April 2017 at 05:09

    Butterworth filter is monotonic in nature

    ReplyDelete
    Replies
    1. Unknown1 May 2017 at 06:34

      Butterworth filter can be used for filters with minimum order1

      Delete
  5. Chaitanya S28 April 2017 at 06:46

    Butterworth filter is also called maximally flat magnitude filter

    ReplyDelete
  6. Parth1 May 2017 at 07:01

    Chebyshev filters have sharper frequency cut-off while butterworth filters have a wide transition band

    ReplyDelete

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