What is Diode?

A diode is an electronic/semiconductor device with two terminals. A diode is used as an electric component in which the current has a unidirectional flow only if the diode works under the specified voltage.


This component has two terminals in which one terminal bears a high resistance, while the other bears a low resistance. 


We have another type of diode which is called the ideal because it bears zero resistance in one direction only and infinite resistance in another resistance. 


On this page, we will understand diode examples, the use of diodes, and the application of diodes.

What are Diodes?

Diodes are composed of semiconductors such as silicon or germanium that have been inserted to produce PN bonds. P-type and N-type semiconductors are combined to produce a PN junction. The letters P and N represent positive and negative, respectively. Semiconductors have a positive cost in the form of holes and a negative cost in the form of free electrons.

The arrow represents the diode and indicates the direction in which the force can flow. When the current flows in this way, it is called forward-biased. When you go to the other side, the arrow has a bar indicating that the wave is blocked. Reversible diodes with current flow in the wrong location. In fact, reversible diodes limit current flow at first but eventually allow others if there is too much flow in the wrong direction.

LEDs are light-emitting diodes designed to emit light. When Zener diodes are reverse-biased, they behave instead of destroying themselves. Varistors are Zener diode reversible and can withstand 1,000 volts. Varactors work in the same way as voltage-varying capacitors do.

Usage of Diodes

Diodes are used in a variety of applications. By removing the signal component, several of them convert current AC to DC current. They are known as rectifiers when used in this position. They act as electric switches and can block voltage spikes, making them ideal for surgical protectors. They are hired to do digital logic. Power supply and voltage doubles are also made with it. The sensors, as well as light on lighting devices and lasers, rely on LEDs. Varactors are used for electronic tuning, and varistors are used for compressing transients in AC lines. Zener diodes are used as voltage regulators, varactors are used for electronic tuning, and varistors are used for compressing transients in AC lines.

Transistors and op-amps are built on the base of the diodes. The p-n junction is the most common diode mode. One (n) object with electrons as the charging conductor closes the second object (p) with holes (depleted areas of electrons acting as well-charged particles) as the charge carriers on this type of diode. The narrowing space forms where they connect, where electrons are dispersed to fill holes in the p-side. This effectively stops the flow of electrons. When a positive voltage is given to the p-side of this junction, electrons may easily move from it to fill the holes, and the current flows into the diode. The shrinkage area increases as the negative bias interacts (i.e., negative voltage is given to the p-side), making the electrons harder to move across.

Extruded glass or a metal electron tube with two electrodes — a badly charged cathode and a well-charged anode — was the first diode. These are employed in electronic circuits such as radio and television receivers as filters and receivers. When the anode (or plate) receives a positive voltage, the electrons released from the hot cathode travel to the plate and then back to the cathode with an external power source. Electrons cannot be removed from the cathode when the wrong voltage is supplied to the plate, and there is no current flow of the plate. As a result, electrons can flow from the cathode to the plate but not to the plate to the cathode in the diode. When the plate is exposed to an alternating voltage, the current flows only when the plate is correct. When an alternating voltage is adjusted, or converted to a direct current, it is said to be adjusted.

Diode Symbol



What is Diode Used For?

One of the most important uses of diodes is as an electronic component for regulating the unidirectional flow of the current.


Diode Examples

Below are the diode examples with the use of diode in day-to-day life:


Zener diodes - They are used to regulate the voltage to protect circuits from high voltage surges,


Avalanche diodes - They are used to electronically tune radio and TV receivers.


Varactor diodes are used to generate radio-frequency oscillations 


Tunnel diodes -  These diodes are used as RF circuits.


Gunn diodes, IMPATT diodes


LED or the light-emitting diode to produce light under the positive waveform of the voltage.


PIN diodes have both P-type and N-type standard regions, but the space between the two areas is the intrinsic semiconductor, and these diodes are not doped.


Variable capacitance diodes for tuning.

Do You Know?

A diode appears to be an open circuit with a negative voltage that looks like a short circuit. Since the diode shows some inefficiency, the graph between the current and voltage appears non-linear. 


One of the incredible and simple two-pin semiconductor devices like a diode is vital in modern electronics. 


So, we find the application of diode in various fields, some of these are as follows:

Application of Diode

  • Rectifying a voltage: turning AC into DC voltages

  • Drawing signals from a supply

  • Controlling the size of a signal

  • Mixing (multiplexing) signals

  • As freewheeling of the inductive energy

What is the Use of Diodes?

Below are the real-life applications of a diode:

1. Rectifying a Voltage 

We use diodes for converting AC power to DC. A single diode or four diodes can convert 110V household power to DC by forming a half-wave (single diode) or a full-wave (four diodes) rectifier. 


So, how does it happen?


The diode allows only half of the AC waveform to pass through it. When this voltage wave charges a capacitor, the output voltage seems to be a steady DC voltage with a small voltage waveform. 


Using a full-wave rectifier makes this process more efficient by routing the AC pulses in a way that both the positive and negative halves of the input sine wave are seen as only positive pulses, constructively doubling the frequency of the input pulses to the capacitor, which helps to keep it charged and remit a more stable voltage.


2. Diodes and Capacitors 

Diodes and capacitors can create varying voltage multipliers to generate a small AC voltage and multiply them to create very high voltage outputs. 


Both AC and DC outputs are possible if the right configuration of capacitors and diodes are used.


3. Diode Used as a Flashlight

An LED flashlight is an illuminating light-emitting diode and it glows in the presence of the positive voltage.


4. Photodiode

A photodiode captures current or the light through a collector (like a mini solar panel device), and converts it into a small amount of current.

Why is Diode Used?

1. Diode as a Current Steering Wheel

The basic function for which diode is used is, to steer the current and make sure it flows in the proper direction. 


One area where the current steering capability of diodes is found is, it has a good effect in switching from the power coming from a power supply to power running from a battery. 


When a device is plugged in and charged, just like the cell phone or uninterruptible power supply, the device draws power only from the external power supply and not the battery, and while the device is plugged in the battery draws the power and recharges. As soon as the power source is removed, the battery powers the device so that no interruption is noticed by the user.


2. A Diode Used For Demodulation of Signals

The most common use of diodes is found in removing the negative component of an AC signal. 


Since the negative portion of an AC waveform is usually identical to the positive half, very little information is lost during the process of a wave portion stripping away; therefore, leading to more efficient signal processing.


The demodulation of signals is commonly used in radios as the component of the filtering system to draw the radio signal from the carrier wave.

FAQs (Frequently Asked Questions)

1. How a diode is used as a voltage-controlling device?

Diodes work as a protective shield for sensitive electronic components. 

When we use a diode as a voltage protection device, it becomes nonconducting under normal working conditions, and therefore, it suddenly shorts a high-voltage spike a.ka. current spike to the ground where it cannot damage an IC. 

The diode is specifically designed to conduct the flow of current in the reverse direction after reaching a specified voltage.

There are some specialized diodes called transient voltage suppressors, they are designed especially for over-voltage protection and can handle very large power spikes for short periods, a typical description of a voltage spike or the current spike damages electronic components and shorten the life of an electronic product; this is the place where the diode comes into play.

2. Describe the zener diode.

A Zener diode is a semiconductor device that allows either the forward or the backward flow of the current. The diode usually comprises a p-n junction, which is heavily doped. In a Zener diode, high doping is done to the semiconductor material to make it more conductive. Because of the presence of high impurities, the depletion region of the diode becomes very thin. Also, the intensity of the electric field increases across the depletion region, due to heavy doping even if a small voltage is applied. The Zener diode bears a reverse-breakdown voltage at which the diode starts conducting the electric current, and continues to remain in the reverse-bias mode. The voltage drop across the diode remains constant irrespective of the voltage applied, and this characteristic of the Zener diode makes it suitable for voltage regulation.

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