DEFINITIONS DIODE
In electronics, a diode is bersaluran two active components (thermionic diodes may have a third channel for heating). Diodes have two active electrodes in which electrical signals can flow, and most of the diodes are used because of its characteristics in one direction. Diodes varikap (Variable Capacitor / condenser variable) is used as voltage controlled capacitors.

Unidirectional properties owned most types of diodes are often called menyearahkan characteristics. The most common function of the diode is to allow electric current to flow in one direction (called the forward bias condition) and to hold the flow from the opposite direction (called a reverse bias condition). Therefore, the diode can be thought of as an electronic version of the valve in the transmission fluid.


WORKING PRINCIPLE
Thermionic diode working principles were rediscovered by Thomas Edison on February 13, 1880 and he was given a patent in 1883 (U.S. Patent 307,031), but not developed further. Braun patented the crystal rectifier in 1899. Braun's discovery was further developed by Jagdish Chandra Bose into a useful device for radio detector.

Most of the current diode based on semiconductor pn meeting technology. In the pn diode, current flows from p-type side (anode) to the n-type side (cathode), but does not flow in the reverse direction.
Another type of semiconductor diode is a Schottky diode formed from a meeting between the metal and semiconductor (Schottky barrier) instead of the conventional pn meeting.