In electronics, even the most minute components can be the key to a system's operation. One such unsung hero is the electrical diode—a semiconductor component that permits current flow in one direction while preventing it in the other direction. Simple to look at but forceful in action, diodes play a crucial role in rectifiers, voltage regulators, signal demodulators, and many more. This blog offers a detailed description of electrical diodes, their types, operations, and applications in the real world.
What is an Electrical Diode?
An electrical diode is an electronic component with two terminals that mostly allows current to flow in one direction. It consists of a semiconductor material, usually silicon or germanium, and has a p-n junction—a p-type and n-type material boundary.
The terminals of a diode are referred to as:
- Anode (+)
- Cathode (-)
When the anode is more positive than the cathode, the diode is "forward biased" and current can flow. When the cathode is more positive, the diode is "reverse biased" and stops current.
This characteristic of one-way current is enormously valuable when controlling electrical energy in a predictable and controlled manner.
How Do Diodes Work?
At the heart of a diode's operation is the p-n junction. Here's a brief overview of how it works:
- P-type material contains a surplus of holes (positive charge carriers).
- N-type material contains excess electrons (negative charge carriers).
When the diode is forward biased, holes and electrons flow towards the junction so that current flows. When reverse biased, the charge carriers are driven away from the junction so that a depletion region forms to prevent the flow of current.
This capability of functioning as a switch that's voltage polarity-controlled is what characterizes the basic operation of all diodes.
Types of Electrical Diodes
There are several types of diodes, each with unique properties tailored to specific functions. Below are some of the most commonly used:
1. Standard PN Junction Diode
This is the basic diode used for rectification—converting AC (alternating current) to DC (direct current). It's widely used in power supply circuits.
2. Zener Diode
Zener diodes permit current flow in the reverse direction after a certain voltage level is achieved. They are utilized for voltage regulation, safeguarding circuits against overvoltage situations.
3. Schottky Diode
Schottky diodes provide low forward voltage drop and high-speed switching. They're typically employed in high-speed switching and power rectification in power supplies.
4. Light Emitting Diode (LED)
An LED produces light when it is forward biased. They are employed in indicators, displays, and lighting.
5. Photodiode
The diode creates current due to exposure to light. They find frequent usage in optical communications, detection of light, and protective systems.
6. Tunnel Diode
These diodes contain negative resistance via quantum tunneling and have application in microwave circuits and high-frequency oscillators.
7. Varactor Diode
Called the varicap too, it serves as a variable capacitor on being reverse-biased. They find use in tuning devices as well as in RF circuits.
Key Applications of Electrical Diodes
Diodes find application in almost every area related to electronics, ranging from domestic appliances to intricate industrial systems. Some of the most important applications are listed below:
1. Rectification
This is perhaps the most prevalent application. Diodes rectify AC to DC, and therefore they find applications in power supplies employed in electronics such as mobile chargers, televisions, and computers.
2. Voltage Regulation
Zener diodes are employed in voltage regulation in circuits so that components get a stable power supply.
3. Signal Demodulation
In communication systems, diodes retrieve sound from radio signals. It
