Diode is a kind of asymmetrical double electrode conductance electronic components. Ideal diode in the forward conductive between its two electrodes (anode and cathode) have infinitely small resistance, and the reverse when there are infinite resistance, ie, the current is allowed to flow from a single direction only through the diode.
Diode having an anode and a cathode two terminals, current can only flow to a single direction. That is, the cathode current may flow from the anode, and not from the cathode to the anode. To diode possess one-way nature of such applications, often called "rectification" function. In the vacuum tube, with a voltage applied between the electrodes so that hot electrons can reach the anode from the cathode, thus rectifying effect. The alternating current into direct current, comprising a radio receiver for a radio signal modulation, are accomplished by the rectifier.
Reverse circulation because of its forward blocking characteristics, diode can be thought of as an electronic version of a check valve. However, in practice, diodes and do not exhibit such a perfect switch resistance, but showing a more complex non-linear electrical characteristics - which are determined by the specific type of diode technology. In general, only in the forward reaches the threshold voltage, the diode will start to work (this state is called forward bias) A change in the voltage drop across the diode is forward biased only to do with current, and is a function of temperature. Therefore, this feature can be used to the temperature sensor or reference voltage.
Semiconductor diode non-linear current - voltage characteristics, thereby forming an impurity may be different depending on the selected semiconductor material and a semiconductor doped with different impurities to alter.
Diode characteristics after the change in the use of switches used in addition to the way, there are many other features, such as: used to adjust the voltage (Zener diode), thereby limiting the high-voltage protection circuit (APD), radio tuner (varactor), generating a radio frequency oscillation (tunnel diode, Gunn diode, IMPATT diode) and generate light (light emitting diode).
Semiconductor diode, there is the use of P-type and N-type joints PN junction of two semiconductor effect, but also the type of Schottky rectifying action to achieve the effect produced by the use of a metal-semiconductor bonding. If the PN junction type diode, the P-type anode side is, N-type side is a cathode.
