# Piecewise linear diode model?

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

1. ### 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*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,482
2,830
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

43
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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?

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Apr 4, 2010

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5. ### 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.