I am trying to calculate input impedence of a MFB low pass filter. What I need is the symbolic expression as simple as possible so that later I fill in the values and get the impedence itself:

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I am not sure if I am on the right track...specially about the current directions I choosed. would somone kindly verify the steps?

What I need obviously is a simple equation with no current in it!

enter image description here

  • \$\begingroup\$ I always hated these stuff ....:) \$\endgroup\$
    – xsari3x
    Feb 12, 2012 at 11:57
  • \$\begingroup\$ what's the reason of "-i3" ? \$\endgroup\$
    – xsari3x
    Feb 12, 2012 at 12:06
  • 1
    \$\begingroup\$ See my answer at math.stackexchange.com/a/108866/18398 \$\endgroup\$ Feb 13, 2012 at 13:02
  • 1
    \$\begingroup\$ Closed as off-topic??? This is clearly electronics. Voted to reopen! \$\endgroup\$
    – stevenvh
    May 12, 2012 at 15:10
  • 1
    \$\begingroup\$ Why is this closed? I don't know how to vote to reopen. \$\endgroup\$ May 28, 2012 at 23:42


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