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How to design an analog filter with arbitrary amplitude-frequency response?

  1. Oct 5, 2009 #1
    We can easily design an digital filter with arbitrary amplitude-frequency response, but if we are required to use an analog filter to implement it, how to design? Any suggestion or reference to related paper would be appreciated. Thanks!
  2. jcsd
  3. Oct 5, 2009 #2


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    Staff: Mentor

    Welcome to the PF. I googled Analog Filter Tutorial, and got lots of good hits. Are these what you are looking for?


  4. Oct 5, 2009 #3


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    You can't. At least not if you want reasonable phase response. Digital filter are usually implemented as FIR filters whereas analog filters are always IIR filters, the latter are much more limited than FIR and high-order IIR filter have lots of problems.

    The reason why you can't implement a FIR filter using analog circuits is that they are not causal, i.e. in order to implement a FIR filter you need some form of memory (buffer) which is impossible using analog circuits (you can of course build a digital circuit using analog components, but what would be the point?).
  5. Oct 5, 2009 #4
    Thank you f95toli, although the reply is depressing. But I believe there will be a way out despite these shortcomings against analog filter. After all, analog circuit has low latency and low power consumption, so worth our effort.
    Thank you berkeman too.
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