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Piecewise linear diode model?

Discussion in 'Electronics Homework Help' started by Ledwardz, Dec 27, 2010.

  1. Ledwardz

    Ledwardz

    43
    0
    Dec 21, 2010
    hi, I've been asked to draw a piecewise linear model of a diode and state the function of each component in the model.


    Am i right in thinking that this would be a diode in series with a resistor from a DC supply?

    in which case i presume its silicon (doesn't say) and so has a cut in voltage of 0.7V
    which creates a graph with
    Id on the y axis
    Vd on the x axis
    and a curve that stays flat until 0.7v when it rises.

    then i presume the resistor will have a large voltage drop across it as well as reducing the current.

    and a silicon diode allows current to only flow in one direction

    somehow though i figure this is not what the question wants me to do (its worth 6 marks) any ideas?

    Thanks, Lee.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,178
    2,690
    Jan 21, 2010
    There are several major features of a reverse biased junction that I might try to model.

    There are also non-linearity in the forward biased V vs I relationship.

    How far do you have to go? Dunno. It all depends on what you've been taught.
     
  3. Ledwardz

    Ledwardz

    43
    0
    Dec 21, 2010
    errrrr only been doing electronics for 2 month and that doesn't seem to ring a belI. I did actually find an example where it said draw a piece wise linear but it gave component values so you could work out the current etc...... and again they had just drawn the v to I of the diode but had mentioned that it was to find an approximation and drawn straight lines on the curve then used 1/rf to work out gradient of slope.

    what would be the most basic parts you would mention or draw?
     
  4. Laplace

    Laplace

    1,252
    184
    Apr 4, 2010

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  5. Ledwardz

    Ledwardz

    43
    0
    Dec 21, 2010
    cheers, i think ill just leave it like that example with one sector. they can't expect much more than that tbh we havn't been doing it for very long.
     
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