What is a precision diode?

A precision diode is a diode with 0V (or near 0V) voltage drop when forward biased, unlike a normal diode which has a finite forward voltage drop of typically 0.2 to 0.8V depending on diode technology.

It is typically implemented with an Operational Amplifier that has a normal diode somewhere in it's feedback path. The circuit utilizes the gain of the Op-Amp to compensate for the finite voltage drop of the diode. Several variations of the implementation exists.

Some applications for precision diodes are

• Rectification or detection of signals with low amplitude
• Voltage gating (selection of the highest or lowest of several voltages)
• Voltage references (replacing Zener diodes)