Use of Diode: Definition, Usage, Types, Application and Examples

Use of Diode Overview

What is the use of Diode? A diode is a semiconductor-based dispositive with two terminals or electrodes that operates as an on-off switch (di-ode). When the diode is turned "on," it forms a short circuit and enables all current to pass through it. When turned off, it behaves like an open circuit and does not conduct any electricity. A diode's anode and cathode terminals are composed of P and N materials, respectively. The voltage applied to these connections can be adjusted to power diodes. When the voltage applied to the anode is positive in proportion to the voltage applied to the cathode, the diode is said to be in forward bias. Diodes are used as rectifiers, radio modulators, power converters, logic gates, and even to monitor the temperature of electrical circuits.

What is a Diode?

1. A diode is an electronic device that allows current to flow in one direction while blocking it in the opposite direction. It is made up of a P-type semiconductor and an N-type semiconductor that are joined together to form a PN junction.
2. When a positive voltage is applied to the P-type semiconductor and a negative voltage is applied to the N-type semiconductor, the diode becomes forward-biased, allowing current to flow through it. However, when the polarity of the applied voltage is reversed, the diode becomes reverse-biased, and the current flow is blocked.
3. Diodes are commonly used in electronic circuits to rectify AC voltage to DC voltage, as voltage regulators, as clamping and protection devices, and in various other applications.

Use of Diode

Diodes are electronic components that have several important uses in electronic circuits. Some of the most common uses of diodes include:

Use of Diode as a Rectifier

1. The rectification of AC to DC electricity is the most common and significant application of a diode.
2. Diodes can be used to construct various kinds of rectifier circuits.
3. The most common types are half wave, full wave center tapped, and full bridge rectifier circuits. A single or a combination of four diodes is used in most power conversion applications.

Use of Protection Diodes

1. Diodes are frequently used to protect integrated circuits against electrostatic discharge.
2. An electrostatic diode event is a rapid discharge of charge between two bodies of distinct potentials.
3. Electrostatic discharge accidents are quite likely to occur during the manufacturing and lifetime of a chip whose pins come into contact with machinery and, on occasion, people.
4. To safeguard the chip from harmful voltages, a set of diodes can be added at the input and output pins.

Use of Diode as Power Conversion

1. Rectifiers are diode-based devices that convert alternating current (AC) electricity to direct current (DC).
2. A common example is automotive alternators where the diode outperforms the commutator of older dynamos.
3. Cockcroft–Walton voltage multipliers also use diodes to convert AC into greater DC voltages.

Use of Diode as Radio Demodulation

1. The diode's first application was the demonstration of amplitude modulated radio broadcasts.
2. The Amplitude Modulation signal is composed of alternating positive and negative voltage peaks whose amplitude or "envelope" is proportional to the original audio signal but has a zero average value.
3. The crystal diode rectifies the Amplitude Modulation signals, resulting in a signal with the required average amplitude.
4. A simple filter is used to obtain the average value, which is then fed into an audio transducer, which creates sound.

Use of Diode as Temperature Measuring

1. Diodes can be used as a temperature monitoring device because the forward voltage drop across a diode is temperature dependent.
2. The voltage looks to have a positive temperature coefficient, so it depends on doping concentration and operating temperature according to the Shockley ideal diode equation.
3. The temperature coefficient might be negative as in normal thermistors or positive as in temperature sensing diodes that operate at temperatures below 20 degrees Kelvin.

Use of Diode in Logic Gates

1. Digital logic operations can also be performed using diodes.
2. The forward and reverse-biased conditions of a diode are equivalent to the low and high impedance states of a logic switch respectively.
3. As a result, the diode may execute logic operations like ‘AND', ‘OR' gates.

Types of Diode

There are many different types of diodes, each with their own unique properties and applications. Some of the most common types of diodes include:

1. Rectifier Diodes:These are the most common type of diode, used to convert AC voltage to DC voltage in power supply circuits. Rectifier diodes can handle high current and are available in a variety of packages, including axial lead and surface mount.
2. Zener Diodes:These diodes are designed to work in the reverse breakdown region, allowing them to maintain a constant voltage output even when the input voltage varies. Zener diodes are often used as voltage regulators in electronic circuits.
3. Schottky Diodes:These diodes have a lower forward voltage drop than standard rectifier diodes, making them more efficient. Schottky diodes are commonly used in power supply and switching circuits.
4. Light Emitting Diodes (LEDs): These diodes emit light when a current flows through them, making them useful for lighting applications. LEDs are available in a variety of colors and brightness levels, and are often used in indicator lights, automotive lighting, and displays.
5. Tunnel Diodes:These diodes exhibit a negative resistance region in their current-voltage characteristic, making them useful in oscillator and amplifier circuits.
6. Varactor Diodes: These diodes have a variable capacitance that changes with the applied voltage, making them useful in frequency control circuits.
7. PIN Diodes:These diodes have a high-resistance region between the p and n regions, allowing them to act as variable resistors in RF and microwave circuits.
8. Photodiodes: These diodes convert light into an electrical signal, making them useful in applications such as light sensors and photovoltaic cells.
9. Avalanche Diodes: These diodes operate in the reverse breakdown region, and can handle high levels of voltage and current. Avalanche diodes are often used in protection circuits and high voltage power supplies.

Use of Diode: Properties

Diodes are electronic components that exhibit unique properties that make them useful in a wide range of applications. Some of the key properties of diodes include:

1. Nonlinearity:One of the most important properties of diodes is their nonlinear behavior. When the voltage across a diode is below a certain level, the diode does not conduct current. However, when the voltage exceeds this level, the diode begins to conduct current, allowing it to be used as a switch or a rectifier.
2. One-Way Conductivity: Diodes allow current to flow in one direction only. This property makes them useful in rectifier circuits, where they can be used to convert AC voltage to DC voltage.
3. Low Resistance in the Forward Direction:When a diode is forward-biased, it offers very low resistance to the flow of current. This property makes diodes useful in voltage regulation and signal conditioning circuits.
4. High Resistance in the Reverse Direction:When a diode is reverse-biased, it offers very high resistance to the flow of current. This property makes diodes useful as protection devices, as they can limit the voltage that reaches sensitive components.

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Use of Diode: Application

1. Rectification:One of the primary applications of diodes is rectification, where they are used to convert AC voltage to DC voltage. This is a key function in power supplies for electronic devices.
2. Voltage Regulation: Zener diodes are used as voltage regulators in electronic circuits. They maintain a constant voltage even when the input voltage varies.
3. Signal Conditioning:Diodes are used to condition signals in electronic circuits, such as clipping or limiting voltage or shaping waveform.
4. Protection:Diodes are used as protection devices in electronic circuits to protect sensitive components from voltage spikes and reverse voltage.
5. Logic Gates:Diodes are used in the construction of logic gates in digital circuits. Logic gates are the building blocks of digital circuits and are used to perform operations such as AND, OR, and NOT.
6. Lighting: Light Emitting Diodes (LEDs) are a type of diode that emit light when a current flows through them. LEDs are commonly used for lighting applications and are much more energy-efficient than traditional incandescent light bulbs.
7. Switching: Diodes can be used as switches in electronic circuits, allowing them to be turned on and off based on the input signal.

Use of Diode: Equations

Diode equations are of two types: Forward Bias and Reverse Bias.

Forward Bias

1. The state that allows current to flow through the pn junction is known as forward bias.
2. VBIAS is the name for the external bias voltage.
3. The resistor keeps the forward current low enough to avoid damaging the diode.
4. The negative side of VBIAS is connected to the n area of the diode in the forward bias, while the positive side is connected to the p region.
5. The bias voltage VBIAS must be more than the barrier potential. For germanium diodes the bias voltage must be greater than 0.3V and for silicon diodes it must be greater than 0.7V.

Reverse Bias

• When the diode is reverse-biased a very little drift current flows across the junction due to thermal stimulation.
• Reverse bias is a condition that prevents current from flowing through the diode.

Use of Diode: Points to Remember

1. The greatest forward current is restricted by the diode's ability to dissipate heat.
2. When a p-n junction diode is forward biased, it has a low resistance; when it is reverse biased, it has a high resistance.
3. A solar cell converts light energy to electrical energy. It is used in the production of energy.
4. In the early 1900s, the first vacuum diode was created as the first semiconductor-based diode.
5. When the half-wave rectifier load resistor is replaced with a grounded capacitor, the peak value of the input signal can be detected.
6. A center-tapped transformer is used to generate fully differential output signals that are rectified by diodes.
7. The input voltage exceeds the capacitor's-maintained voltage until the diode remains turned off.