Electronic – Help with trying to understand Voltage controlled current sources


I have been looking for weeks for an article or anything that could explain to me how a voltage controlled current source works. I want to know if it's possible to create a VCCS that changes according to a function. What I mean by this is if you can make it so that if the voltage changes according to a function the current changes how you want it to. Can anyone explain to me how a VCCS works and how to make it work according to a function?

Best Answer

One possible way to do it:


simulate this circuit – Schematic created using CircuitLab


This works because the current into the + and - inputs of the OP-AMP is zero (by definition) and the voltage between them is also zero (by definition). As the OP-AMP is used as a buffer (- input directly connected to output), the voltage at R1 is U1, so the current through R1 is


and because there's no way out for that current (by definition), that's also the current through R2. Regardless of the value of R2.