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Homework Help: Quick question on diode circuit

  1. Sep 6, 2011 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
    Just want to know whether I have the right idea: so to determine the reverse saturation current (IS), I just determine it for each value of VD that was given? So finding IS for 0.6, 0.65, 0.7 etc?

    The question seems to be divided into two parts, one that just asks for the reverse saturation current, and then to sketch a graph for points VD=0.6, 0.65 etc. But it's not as if we're already given an initial VD value to determine the reverse saturation current, so I'm guessing you just find it for the various values given?

  2. jcsd
  3. Sep 6, 2011 #2


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    - Replace the voltage source and resistors with a Thevenins equivalent.
    - From the load line : Id = 6 - Vd (I in mA) you can find Vd.
    - Sub the now known values of Vd and Id into Id = Is e^(Vd/0.0375) to find Is.

    Note: Id and Is both mA in that equation. And yes it's ok to leave out the "-1".
    Last edited: Sep 6, 2011
  4. Sep 7, 2011 #3
    Actually I already figured it out using nodal analysis, but thanks anyway. And I just tried using Thevenin's theorem, and it worked out too :)
    Last edited: Sep 7, 2011
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