What Is An Ideal Current Source?

An ideal current source is a simple model for many current sources. It is reminiscent of the ideal voltage source - but with voltage and current interchanged. Here is the story.

* There is a special circuit symbol for an ideal current source. See below

* IL = constant, no matter what the terminal voltage is.
* The plot of load current against terminal voltage is similar to the plot for an ideal voltage source, but voltage and current are interchanged. Here is the plot.

Notice that an ideal current source is somewhat similar to an ideal voltage source. However, when you use an ideal source - usually when doing circuit analysis- there is a significant difference in the analysis. However, that's getting ahead of the story. We first have to worry about how you would "use" an ideal source, when we know that there is no such thing as an ideal source, i.e. a source that is "perfect" in some way.