butterworth filter

Discussion in 'Homework Help' started by josh007, Sep 20, 2015.

  1. josh007

    Thread Starter Member

    Sep 20, 2015
    40
    1
    Hi. Help Please. I need the experts to please verify my solution thanks.
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,140
    1,789
    For starters, I don't think your transfer function represents a Butterworth Filter. Why do you think it does?
    Also -- what is with the negative resistance? No passive component is capable of having such a behavior.
     
    josh007 likes this.
  3. josh007

    Thread Starter Member

    Sep 20, 2015
    40
    1
    Hi Sir. Please can you advise me on what needs to be done. I just feel like giving up on this subject. I need help please. Please guide me.

    I thought to make it look like a third order butterworth filter. Where can I find info that will help me to answer this.

    thanks
     
  4. recklessrog

    Member

    May 23, 2013
    338
    102

    Go to www.nuhertz.com and download filter free 2012, very useful free software
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,140
    1,789
    I think you might want to start with an expression for Zin(s). Hint: your schematic looks like the equivalent circuit for an active device. The diamond symbol with the arrow inside "looks like" a current source, but with a value of 2V1, it has the wrong units. If instead it is a voltage source, then you have an amplifier with a gain of 2. Knowing what that symbol represents would be most helpful.
     
  6. josh007

    Thread Starter Member

    Sep 20, 2015
    40
    1
    Hi sir. This is the solution that I have derived. Is this correct? I really am battling with this subject. Thanks.
     
  7. Papabravo

    Expert

    Feb 24, 2006
    10,140
    1,789
    The picture of your work is very difficult to read, especially the subscripts, and the drawing is not labeled. So I don't know what the quantities refer to. Try not to take pictures of a page on an angle it hurts my eyes to try and read it.

    Isn't
    Z_{in}(s) = \frac{1}{1+2s}|_ {\scriptsize s=j\omega}
     
    Last edited: Sep 21, 2015
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