It has long been known that the simple combination of a depletion-mode MOSFET (and before these were available, a JFET) and a resistor made a simple, serviceable current source such as that seen on ...
The following application note shows how to create a circuit that converts the low output current from a photo-diode into a fast-responding voltage. To view the application note, click on the URL ...
A diode is a semiconductor device that allows electrical current to flow in one direction while blocking it in the other.