Wednesday- 18th May 2022


What is Diode? How is it Work?

‘A diode is a two-terminal semiconductor device that conducts current in a circuit. The resistance of one direction is almost zero and the resistance of the opposite direction is much higher.

It has two electrodes, one anode, and the other a cathode. Diodes are mainly made of semiconductor silicon and germanium.  A diode is made by connecting a P-type semiconductor and an N-type semiconductor.

The junction of two semiconductors is called the P-N junction. Used in diode rectification, modulation, reverse voltage protection, high voltage protection, clamping, clipping, logic circuit, etc. The diode is made by placing two different regions side by side in the semiconductor diode, p-region, and n-region. The p-region of the diode is called the anode and the n-region is called the cathode.

This diode only performs forward bias conditions. When the diode does not conduct conduction in reverse biasing, it behaves like an open circuit (resistance infinity) and currently does not flow. Since the diode carries current in one direction, it is called a one-way switch.

The main function of a common diode is to carry current in a forwarding direction. Current, on the other hand, interrupts the current when it flows in the reverse direction. How the diode acts as a one-way valve.

Different terms related to diodes:

Forward Biasing

Forward biasing is the current that flows easily through the p-n junction. Forward biasing is done by connecting the positive edge of the source in the P-type electrode and the negative edge of the source in the N-type electrode.

Reverse Biasing

Reverse biasing is the current that cannot easily flow through a p-n junction. Reverse biasing is done by connecting the negative edge of the source in the P-type electrode and the positive edge of the source in the N-type electrode.

Breakdown Voltage

By reverse biasing the p-n junction diode, the p-n junction breaks after exceeding a certain voltage as the reverse voltage continues to increase and excessive amounts of current begin to flow. This state of the diode is called breakdown and the voltage at this time is called break down voltage. The breakdown voltage of diodes of different ratings is different.


Knee Voltage or Offset Voltage

The minimum voltage at which the p-n junction diode conducts forward bias is the ni-voltage. Silicon has a Ni-voltage of 0.7 and Germanium has a Ni-voltage of 0.3.

Peak Inverse Voltage or PIV

The maximum reverse voltage of the diode is the peak inverse voltage

Maximum Reverse Repetition Voltage or MRRV

A.C. at the input of a diode. The maximum number of times the reverse bias is obtained per second when supplied is the maximum reverse repeat voltage. This is the A.C. Depending on the frequency.

Different types of diodes

  • Small Signal Diode
  • Large Signal Diode
  • Zener Diode
  • Light Emitting Diode or LED
  • Photodiode
  • Laser Diode
  • Constant Current ‘Diode
  • Schottky Diode
  • Shockley Diode
  • Step Recovery Diode
  • Tunnel Diode
  • Varactor Diode
  • Transient Voltage Suppression Diode or TVS Diode
  • Gold Doped Diode
  • Super Barrier Diode
  • Peltier Diode
  • Crystal Diode
  • Avalanche Diode
  • Silicon Controlled Rectifier
  • Vacuum Diode
  • PIN Diode
  • Point Contact Device
  • Gunn Diode

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