# Create circuit from current–voltage characteristic

I'm trying to create a circuit from a given current–voltage characteristic like this:

I want to use ideal diodes/ideal voltage source/ideal current source

So my idea was for the dotted graph the left circuit and for the solid graph the right circuit

(in case you wonder I created it with https://www.circuitlab.com)

Is that the right track - and if not what do I need to do then?

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There's a serious problem with the right side circuit. The series current source means that there can only be 1A of current clockwise. The series diode means that there can only be no current clockwise. That's a contradiction. Where is the graphed voltage in either of these circuits? –  Alfred Centauri Jul 4 '12 at 22:35

You can use arbitrary behavioral sources (also see #1 #2 for more info) to model this piecewise-linear device for simulation.

For example, by defining a current source with current expression "MAX(0, V()/0.1)", we've effectively modeled a diode that is open-circuit with reverse bias, and looks like a 0.1 ohm resistor with forward bias: (open and run simulation here)

You can now use this source I1 in more complicated circuit simulations (to simulate a switching power supply with an ideal diode, for example). And you can adjust the expression slightly in order to put the knee exactly where you'd like it.

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