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Saturday, October 1, 2016

Type of Diode¦ Different Types of Diode¦


A semiconductor diode's current voltage characteristic can be tailored by selecting the semiconductor materials and the doping impurities introduced into the materials during manufacture. These techniques are used to create special purpose diodes that perform many different functions. For example, diodes are used to regulate voltage (Zener diodes), to protect circuits from high voltage surges (avalanche diodes), to electronically tune radio and TV receivers (varactor diodes), 



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In this video, the manner in which they do so can vary. Several types of diodes are available for use in electronics design. Some of the different types are.



Light Emitting Diode (LED):- It is one of the most popular type of diodes and when this diode permits the transfer of electric current between the electrodes, light is produced. In most of the diodes, the light (infrared) cannot be seen as they are at frequencies that do not permit visibility.


Laser Diode:- This type of diode is different from the LED type, as it produces coherent light. These diodes find their application in DVD and CD drives, laser pointers, etc.

Avalanche Diode:- This type of diode operates in the reverse bias, and used avalanche effect for its operation. The avalanche breakdown takes place across the entire PN junction, when the voltage drop is constant and is independent of current. Generally, the avalanche diode is used for photo-detection, wherein high levels of sensitivity can be obtained by the avalanche process.

Schottky Diodes:- These diodes feature lower forward voltage drop as compared to the ordinary silicon PN junction diodes. The voltage drop may be somewhere between 0.15 and 0.4 volts at low currents, as compared to the 0.6 volts for a silicon diode. Schottky diodes are used in RF applications, rectifier applications and clamping diodes.

Zener diode:- This type of diode provides a stable reference voltage, thus is a very useful type and is used in vast quantities. The diode runs in reverse bias, and breaks down on the arrival of a certain voltage. A stable voltage is produced, if the current through the resistor is limited. In power supplies, these diodes are widely used to provide a reference voltage.

Constant Current Diodes:- It is also known as current regulating diode or constant current diode or current limiting diode or diode-connected transistor. The function of the diode is regulating the voltage at a particular current. It functions as a two terminalcurrent limiter. In this JFET acts as current limiter to achieve high output impedance. The constant current diode symbol is shown below.

Photodiode:-  Photodiodes are used to detect light and feature wide, transparent junctions. Generally, these diodes operate in reverse bias, wherein even small amounts of current flow, resulting from the light, can be detected with ease. Photodiodes can also be used to generate electricity, used as solar cells and even in photometry.

Varicap Diode or Varactor Diode:-This type of diode feature a reverse bias placed upon it, which varies the width of the depletion layer as per the voltage placed across the diode. This diode acts as a capacitor and capacitor plates are formed by the extent of conduction regions and the depletion region as the insulating dielectric. By altering the bias on the diode, the width of the depletion region changes, thereby varying the capacitance.

 Peltier diodes:- This diode is used as heat engine and sensor for thermoelectric cooling.

Rectifier Diode:- These diodes are used to rectify alternating power inputs in power supplies. They can rectify current levels that range from an amp upwards. If low voltage drops are required, then Schottky diodes can be used, however, generally these diodes are PN junction diodes.

Small signal or Small current diode:- These diodes assumes that the operating point is not affected because the signal is small

 Large signal diodes:-The operating point in these diodes get affected as the signal is large.

Transient voltage supression diodes:- This diode is used to protect the electronics that are sensitive against voltage spikes.

Avalanche diode:- This diode conducts in reverse bias condition where the reverse bias volage applied across the p-n junction creates a wave of ionization leading to the flow of large current. These didoes are designed to breakdown at specific reverse voltage in order to avoid any damage.

 Gold doped diodes:- These diodes use gold as the dopant and can operate at signal frequencies even if the forward voltage drop increases.

 Super barrier diodes:-These are also called as the rectifier diodes. This diodes have the property of low reverse leakage current as that of normal PN junction diode and low forward voltage drop as that of Schottky diode with surge handling ability.

 Point contact diodes:- The construction of this diode is simpler and are used in analog applications and as a detector in radio receivers. This diode is built of N type semiconductor and few conducting metals placed to be in contact with the semiconductor. Some metals move from towards the semiconductor to form small region of  P tpye semiconductor near the contact.


Gunn diode:- This diode is made of materials like GaAs or InP that exhibit a negative differential resistance region.

Crystal diode:- These are a type of point contact diodes which are also called as Cat’s whisker diode. This didoe comprises of a thin sharpened metal wire which is pressed against the semiconducting crystal. The metal wire is the anode and the semiconducting crystal is the cathode. These diodes are obsolete.



Silicon controlled rectifier:- As the name implies this diode can be controlled or triggered to the ON condition due to the application of small voltage. They belong to the family of Tyristors and is used in various fields of DC motor control, generator field regulation, lighting system control and variable frequency drive . This is three terminal device with anode, cathode and third controlled lead or gate.

 Vacuum diodes:- This diode is two electrode vacuum tube which can tolerate high inverse voltages.



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Type of Diode ¦ Different Types of Diode.¦
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