# Piecewise linear diode model?

#### Ledwardz

Dec 21, 2010
43
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.

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
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.

#### Ledwardz

Dec 21, 2010
43
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.

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?

Apr 4, 2010
1,252

#### Attachments

• The Piecewise Linear Model.pdf
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#### Ledwardz

Dec 21, 2010
43
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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