how to design butterworth IIR filter

Discussion in 'General Electronics Chat' started by vead, Dec 30, 2013.

  1. vead

    Thread Starter Active Member

    Nov 24, 2011
    621
    8
    I want to learn how to design butterworth IIR digital filter with low pass and designed by Z transform method
    what specification I need to design
    I know below
    1) cutoff frequency
    2)stop band frequency
    3)Ripple in pass band
    4)Filter order

    what specification I need to know to design filter?
     
  2. ActivePower

    Member

    Mar 15, 2012
    155
    23
    A little more information would be useful here. Are you looking for a software implementation, an algorithm of some sorts or a procedure for doing hand calculations?

    In any case, there are plenty of resources available online for digital filters. A quick Google look-up resulted in this, this and this (for a Matlab implementation)

    There is also this free ebook on DSP that you might find useful.
     
  3. crutschow

    Expert

    Mar 14, 2008
    12,981
    3,221
    If it's a low-pass filter then you don't normally use the stop band frequency, only the cutoff (corner) frequency and filter order are needed.
     
  4. vead

    Thread Starter Active Member

    Nov 24, 2011
    621
    8
    I want to know procedure for doing hand calculations?
     
  5. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    One of the two best technical books ever. He knows how to explain things.
     
  6. ActivePower

    Member

    Mar 15, 2012
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    @vead: There was some theory in the links I posted earlier. In any case, this looks pretty rigorous. Hope it helps.

    Indeed. I owe a significant part of my DSP know-how to this book. It was a huge help during my Signals course given how dry and math-intensive those tend to become. Just out of curiosity though, which is the other one?
     
  7. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    Programming the Z80 by Ronald Zaks. Another monster who knows how to explain.
     
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