Think of a diode as a one-way street for electricity. When the diode is in the feed direction, the diode allows circulation or current from the anode to the cathode foot. A negative reverse current is blocked, so there is no circuit current.
The most common function of a diode is to allow the passage of an electric current in one direction (called the diode’s forward direction), blocking it in the opposite direction (reverse direction). As such, the diode can be seen as an electronic version of a retention valve. This unidirectional behavior is called rectification and is used to convert alternating current (AC) into direct current (DC). Forms of rectifiers, the diodes can be used for tasks such as extracting modulation from radio signals in radio receivers.
However, diodes may have a more complicated behavior than this simple on / off action due to non-linear current voltages. semiconductor diodes begin to conduct electricity only if there is a certain threshold voltage or a voltage in the direction of advancement of the cut (a state in which the diode is considered to be tilted forward). The voltage drop on a polarized frontal diode varies very little with the current and is a function of temperature; this effect can be used as a temperature sensor or as a voltage reference.
A characteristic voltage current of the semiconductor diode can be regulated by the selection of semiconductor materials and doping impurities introduced into the material during production. These techniques are used to create special diodes that perform different functions.
For example, the diodes are used to adjust the voltage (Zener diodes) to protect the Surge circuits (Avalanche diodes) to electronically regulate radio and TV receivers (varactor diode) to generate oscillating radiofrequency (tunnel diodes, Gunn diodes, IMPATT diodes), and produce light (emission diode). Galleries, Gunn and IMPATT diodes exhibit a negative resistance, which is useful in microwaves and switching circuits.