Operational amplifiers are frequently used to make high-quality current sources in a variety of applications, such as industrial process control, scientific instrumentation, and medical equipment.

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 ...

Before the LT3092, the simplest current source was merely a voltage source with a resistor in series feeding the load resistance. Assuming the load resistance is much smaller than the series resistor, ...