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Simple inverse Laplace using PFE not so simple?

  1. Jun 17, 2015 #1

    When evaluating the step response of a circuit, the resulting Laplace representation is:
    $\frac{I_{pd}}{s^2 C1 R1}$

    If I look this up on a table of Laplace Transforms, this results in $\frac{I_{pd}*t}{C1 R1}$.

    However, I'm struggling to solve this via partial fraction expansion--is there a special trick or step I need to take that would enable me to arrive at the same solution? I don't see where I'm going wrong.

    Last edited: Jun 17, 2015
  2. jcsd
  3. Jun 17, 2015 #2


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    I cannot read this. please write it in another way. It seems to be something like:

    IR / (C1*R1) * ( 1 / s ) which is simply a step function.
  4. Jun 17, 2015 #3
    Sorry, my latex is rusty and i can't figure out how to make it work.
    So, here it is directly Ipd/(R1*C1*s^2).

    In time domain, this results in t*Ipd/(R1*C1). My problem is I can't seem to get there via partial fraction expansion....
    Last edited: Jun 17, 2015
  5. Jun 18, 2015 #4
    Never mind, i figured it out....
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