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Transfer function from a Z = a - i * b number.

  1. Dec 26, 2015 #1
    I have a circuit where after a deduction of the impedance, I have found the output to input voltage relation as Vout/Vin = 2 - 3i

    Can anyone please let me know how can I can convert it to s functions (such as G(s) = 1/1+s) in Matlab so that I can get a transfer function?

    I would appreciate help, or a link to a document if that is preferred.
  2. jcsd
  3. Dec 26, 2015 #2


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  4. Dec 26, 2015 #3
    Thanks..but i swear to God..i have read those...i think i am missing a very small little connection...2 - 3i is supposed to be a resistor and capacitor in series..R and C...and now just have to convert that into s domain...i guess..i would need some more reading...once i have the numerater and denominator, i can just use the matlab function to find the transfer function...as i said...it's been a while since i have done this and just trying to peak some brain from a person who deals with this on a daily basis...

    not trying to be slacker...i will resolve as time progress...
  5. Dec 26, 2015 #4


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    a capacitor is 1/sC and a resistor is R. An inductor is sL. So a series RC is R + 1/sC or you could say it is R + 1/jwC (I use j instead of i) which is R -j/wC

    The impedance of a capacitor is 1/2πfc which is the same as saying 1/wC.
  6. Dec 26, 2015 #5
    yes..you are absolutely correct..:-)...i am a bit suspicious about the frequency and the reason trying to see...if i am missing something while writing the TF...i will most likely take care of this on the coming week and your explanation really helped a lot...much appreciated...
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