This document discusses special diodes such as zener diodes, varactor diodes, LEDs, photodiodes, and laser diodes. It describes how zener diodes can be used for voltage regulation and limiting by maintaining a constant voltage over a range of currents. Varactor diodes have a variable capacitance based on reverse bias voltage. LEDs emit light when forward biased while photodiodes produce a current proportional to light intensity. Other diodes discussed include Schottky diodes, PIN diodes, and tunnel diodes used for RF applications.
The document discusses the zener diode, how it works, its applications, and use in voltage regulation. A zener diode allows current to flow in both directions, maintaining a nearly constant voltage when the reverse breakdown voltage is exceeded. It is commonly used to provide a stable reference voltage for power supplies and other equipment requiring voltage regulation. The zener diode's impedance adjusts to varying input voltages and loads to regulate its designated voltage within a specified operating current range.
A Zener diode allows current to flow from anode to cathode like a normal diode, but also permits reverse current flow above its breakdown voltage. It was named after Clarence Zener who discovered the Zener effect of electron tunneling caused by a strong electric field. A Zener diode can be used as a voltage regulator or voltage reference by maintaining a constant voltage drop across its terminals when reverse biased above its breakdown voltage. Modern Zener diodes provide stable and consistent breakdown voltages through precise doping techniques.
Zener diodes are designed to operate at voltages exceeding their breakdown voltage. They have a specific, manufactured breakdown voltage and are packaged like standard PN junction diodes. Zener diodes can be used to regulate voltages in circuits by maintaining a constant output voltage despite changes in input voltage or output current. Their regulation properties come from operating the diode in its breakdown region above the zener voltage.
This document provides instructions and information for Lesson 3 of a kit building class. It discusses the purpose and types of power supplies, how zener diodes can be used as voltage regulators, transistor basics including NPN and PNP transistors, crystal oscillators and how adding an inductor can change the resonant frequency, troubleshooting circuit problems, and instructions for installing specific components for the lesson including testing procedures.
The document discusses Zener diodes, which are designed to operate reliably in reverse breakdown. Zener diodes have a sharp, well-defined breakdown voltage determined by the doping concentration. There are two types of breakdown mechanisms - Zener breakdown for heavily doped PN junctions and avalanche breakdown for lightly doped junctions. Zener diodes can be used as voltage regulators since their breakdown voltage remains constant, allowing the output voltage to remain stable despite input voltage or load variations by maintaining the current through the Zener. The value of the series resistor in a Zener regulator circuit is calculated based on the input and Zener voltages and the total current.
Diodes and diode circuits are described in the document. Key points include:
- Diodes only conduct current in one direction, blocking it in the other. Forward biased diodes conduct more easily than reversed biased diodes.
- Zener diodes are intended for operation in the breakdown region to provide a stable voltage.
- Rectifier circuits like half-wave and full-wave converters use diodes to convert AC to DC power.
- Voltage regulator circuits employ zener diodes to provide a constant output voltage despite varying input levels.
The document discusses the Zener diode, including its construction, working principle, and applications. A Zener diode is a pn junction device designed to operate in the reverse breakdown region and is used to regulate voltage. It breaks down at a specific voltage level set during manufacturing. Zener diodes regulate voltage by maintaining a constant voltage across their terminals despite variations in line or load. They are often used in power supplies and other equipment requiring a stable reference voltage.
The document discusses the zener diode, how it works, its applications, and use in voltage regulation. A zener diode allows current to flow in both directions, maintaining a nearly constant voltage when the reverse breakdown voltage is exceeded. It is commonly used to provide a stable reference voltage for power supplies and other equipment requiring voltage regulation. The zener diode's impedance adjusts to varying input voltages and loads to regulate its designated voltage within a specified operating current range.
A Zener diode allows current to flow from anode to cathode like a normal diode, but also permits reverse current flow above its breakdown voltage. It was named after Clarence Zener who discovered the Zener effect of electron tunneling caused by a strong electric field. A Zener diode can be used as a voltage regulator or voltage reference by maintaining a constant voltage drop across its terminals when reverse biased above its breakdown voltage. Modern Zener diodes provide stable and consistent breakdown voltages through precise doping techniques.
Zener diodes are designed to operate at voltages exceeding their breakdown voltage. They have a specific, manufactured breakdown voltage and are packaged like standard PN junction diodes. Zener diodes can be used to regulate voltages in circuits by maintaining a constant output voltage despite changes in input voltage or output current. Their regulation properties come from operating the diode in its breakdown region above the zener voltage.
This document provides instructions and information for Lesson 3 of a kit building class. It discusses the purpose and types of power supplies, how zener diodes can be used as voltage regulators, transistor basics including NPN and PNP transistors, crystal oscillators and how adding an inductor can change the resonant frequency, troubleshooting circuit problems, and instructions for installing specific components for the lesson including testing procedures.
The document discusses Zener diodes, which are designed to operate reliably in reverse breakdown. Zener diodes have a sharp, well-defined breakdown voltage determined by the doping concentration. There are two types of breakdown mechanisms - Zener breakdown for heavily doped PN junctions and avalanche breakdown for lightly doped junctions. Zener diodes can be used as voltage regulators since their breakdown voltage remains constant, allowing the output voltage to remain stable despite input voltage or load variations by maintaining the current through the Zener. The value of the series resistor in a Zener regulator circuit is calculated based on the input and Zener voltages and the total current.
Diodes and diode circuits are described in the document. Key points include:
- Diodes only conduct current in one direction, blocking it in the other. Forward biased diodes conduct more easily than reversed biased diodes.
- Zener diodes are intended for operation in the breakdown region to provide a stable voltage.
- Rectifier circuits like half-wave and full-wave converters use diodes to convert AC to DC power.
- Voltage regulator circuits employ zener diodes to provide a constant output voltage despite varying input levels.
The document discusses the Zener diode, including its construction, working principle, and applications. A Zener diode is a pn junction device designed to operate in the reverse breakdown region and is used to regulate voltage. It breaks down at a specific voltage level set during manufacturing. Zener diodes regulate voltage by maintaining a constant voltage across their terminals despite variations in line or load. They are often used in power supplies and other equipment requiring a stable reference voltage.
SEMICONDUCTOR DEVICES AND APPLICATIONS.
Introduction to P-N Junction Diode and V-I Characteristics
Half wave and Full wave rectifiers
Capacitor filters
Zener diode and its Characteristics
Zener Diode as Voltage regulator
This document is a report about Zener diodes and how they can be used as voltage regulators. It defines a Zener diode as a properly doped crystal diode that has a sharp breakdown voltage, allowing it to maintain a constant voltage even as current varies. The document explains that a Zener diode is reverse biased and regulates voltage by dropping excess incoming voltage or conducting additional current to keep the load voltage constant regardless of fluctuations in the input voltage or load resistance.
The document discusses the characteristics and operation of a Zener diode. There are two main breakdown mechanisms for a Zener diode - Zener breakdown and avalanche breakdown. Zener breakdown occurs when the electric field breaks covalent bonds, generating electron-hole pairs. Avalanche breakdown occurs when carriers gain enough energy to break bonds and generate more carriers, continuing in an avalanche effect. A Zener diode operates in reverse bias and exhibits a nearly constant breakdown voltage, making it useful for providing a stable reference voltage.
The document discusses the zener diode, including its construction, working principle, and applications. A zener diode operates in reverse breakdown to regulate voltage. It has a very thin, heavily doped depletion region which allows breakdown at low voltages. Zener diodes are used to provide stable reference voltages for applications like power supplies.
The zener diode is designed to operate in reverse bias and maintain a stable reference voltage within a circuit. It achieves this through a carefully controlled manufacturing process that heavily dopes the silicon pn junction with impurities, creating a very thin depletion region. This allows the zener diode to undergo breakdown at low reverse voltages, enabling it to function as a voltage regulator when placed in reverse bias within a circuit.
Best 3 Applications Involving in Zener Diode Working Functionalityelprocus
Zener diodes are normal PN junction diodes operating in a reverse biased condition. Working of the Zener diode is similar to a PN junction diode in forward biased condition, but the uniqueness lies in the fact that it can also conduct when it is connected in reverse bias above its threshold / breakdown voltage. These are among the basic types of diodes used frequently, apart from the normal diodes.
Zener diodes are designed to operate in reverse breakdown at a specific voltage. They maintain a stable reference voltage through the zener effect which causes a dramatic increase in current below around 6V. A zener diode can be used in a voltage regulator circuit with a series resistor to maintain a constant output voltage across a load despite variations in input voltage or load current. When operating, the zener diode is reverse biased and acts to clamp the voltage at its breakdown level.
This document outlines an experiment to understand how a zener diode can be used as a voltage regulator. It describes how zener diodes have a high doping level that allows them to maintain a constant voltage under reverse bias. The circuit uses a zener diode, resistors, potentiometer and battery to regulate the voltage. By varying the potentiometer, the voltage drop across the zener diode remains constant at its breakdown voltage. Voltage regulators are important in electronics to provide a steady voltage for circuits.
This document contains lecture notes on diode applications and types. It discusses topics like full wave and bridge rectifiers, power supply filters, diode clippers and clampers, zener diodes, varactor diodes, LEDs, photodiodes, and schottky diodes. It provides circuit diagrams and explanations of how each component works, along with example calculations for determining voltage, current, and resistance values.
The zener diode can be used as a voltage regulator. It has two operating conditions: forward bias and reverse bias. In reverse bias, the current remains constant for some voltage values due to minority charge carriers. If the voltage is further increased, the current reaches a maximum value at the reverse breakdown voltage. This sudden increase in current can be due to either the Zener effect or avalanche effect. The zener diode maintains a constant output voltage regardless of fluctuations in the input voltage by keeping the voltage drop across a series resistor equal to changes in the input voltage.
The document discusses the use of Zener diodes as voltage regulators. It begins by describing how Zener diodes allow current to flow in the reverse direction above a certain breakdown voltage. It then discusses different types of Zener diodes categorized by voltage, current, and power ratings. The document explains that Zener diodes can regulate an unsteady input voltage to provide a steady output voltage. It provides an example circuit diagram of a Zener diode regulating a 12V supply down to a steady 8V for a 100mA load. Measurements and component selections are described to illustrate how the Zener diode maintains a constant voltage across varying loads and minor input fluctuations.
This presentation introduces Zener diodes. It discusses that a Zener diode is a silicon pn junction designed to operate in reverse breakdown, maintaining a constant voltage even as current changes. The document examines Zener breakdown characteristics, showing how reverse current increases rapidly at the knee point where breakdown begins. It provides an example calculation of Zener impedance. Applications of Zener diodes discussed include waveform clipping, voltage regulation, and voltage shifting.
The document discusses diodes and their applications. It explains that diodes allow current to flow easily in one direction but block it in the other, acting like a one-way valve. It describes the basic diode characteristics and models. It then discusses how a p-n junction forms and how applying a voltage bias allows current to flow. Different types of diodes are also summarized, including power diodes, signal diodes, and Zener diodes. Two diode circuit applications - a clamp and stiff clamp - are explained briefly.
This document summarizes an experiment performed with a Zener diode. The students measured the voltage and current characteristics of the diode by varying the voltage in one circuit and the load resistance in another. They found the breakdown voltage of the diode experimentally and obtained a second characteristic curve by changing the load resistance. The document then describes the theoretical characteristics and functioning of a Zener diode, including its use as a voltage regulator.
The document discusses light emitting diodes (LEDs). It outlines the major characteristics required of light sources, including small size, minimum distortion/noise, emitting light at wavelengths where fiber has low losses, capable of signal modulation over a wide bandwidth, coupling sufficient optical power, narrow spectral width, and being stable, cheap and reliable. It describes the basic construction of an LED, which consists of a semiconductor diode chip encapsulated in a suitable lens. The document explains the operating principle of LEDs, where electrons recombine with holes at the PN junction, emitting photons of light rather than heat like ordinary diodes. It provides examples of LED applications like power indicators, blown fuse indicators, and light bulbs, noting advantages of LED
Zener diodes allow current to flow in both the forward and reverse directions. In the reverse direction, current only flows when the voltage exceeds the Zener voltage. Zener diodes can be used as voltage regulators by introducing them into a circuit driven by a current source. As the voltage increases past the Zener voltage, the diode draws excessive current from the supply to maintain a constant output voltage. Zener breakdown occurs through heavily doped regions near the contacts, allowing current at a lower voltage than normal avalanche breakdown.
1. ZENER DIODE and It’s Application
2. ZENER DIODE Zener diode are specifically designed to operate under reverse breakdown conditions. These diodes have a very accurate and specific reverse breakdown voltage. OR A Zener diode is a particular type of diode that, unlike a normal one, allows current to flow not only from its anode to its cathode, but also in the reverse direction, when the Zener voltage is reached.
3.Circuit Diagram the most basic Zener diode circuit consist of a single Zener diode and a resister.
The Zener diode provides the reference voltage.
A series resistor must be in place to limit the current into the diode otherwise a large amount of current would flow through it and it could be destroyed.
The document discusses the working principles of zener diodes. It explains that zener diodes are designed to operate in the reverse breakdown region, unlike standard rectifier diodes. There are two types of breakdown that can occur for a reverse biased p-n junction - zener breakdown and avalanche breakdown. Zener breakdown occurs at lower voltages between 2-8V and is used to regulate voltage. The zener diode maintains a constant voltage for changing currents, making it useful in voltage regulator circuits.
El diodo Zener es un tipo especial de diodo diseñado para funcionar en la zona de ruptura e implementado en reguladores de tensión para mantener una tensión constante entre sus terminales a pesar de variaciones en la tensión de entrada, la resistencia de carga o la temperatura. Fue inventado por Clarence Melvin Zener y mantiene una tensión constante cuando se polariza inversamente, distinguiéndose de los diodos de avalancha.
This document discusses the fundamentals of laser diodes, including:
1) Laser diodes use direct bandgap semiconductors where electron-hole recombination emits photons of light equal to the bandgap energy. Population inversion, needed for lasing, can be achieved through heavy doping of both p-type and n-type materials near the depletion layer.
2) Early laser diodes used homojunctions but now use double heterojunctions of GaAs for the active region surrounded by higher bandgap AlGaAs for better optical confinement.
3) Double heterojunction lasers have lower lasing thresholds than earlier designs due to reduced optical losses from improved carrier and light confinement, though
SEMICONDUCTOR DEVICES AND APPLICATIONS.
Introduction to P-N Junction Diode and V-I Characteristics
Half wave and Full wave rectifiers
Capacitor filters
Zener diode and its Characteristics
Zener Diode as Voltage regulator
This document is a report about Zener diodes and how they can be used as voltage regulators. It defines a Zener diode as a properly doped crystal diode that has a sharp breakdown voltage, allowing it to maintain a constant voltage even as current varies. The document explains that a Zener diode is reverse biased and regulates voltage by dropping excess incoming voltage or conducting additional current to keep the load voltage constant regardless of fluctuations in the input voltage or load resistance.
The document discusses the characteristics and operation of a Zener diode. There are two main breakdown mechanisms for a Zener diode - Zener breakdown and avalanche breakdown. Zener breakdown occurs when the electric field breaks covalent bonds, generating electron-hole pairs. Avalanche breakdown occurs when carriers gain enough energy to break bonds and generate more carriers, continuing in an avalanche effect. A Zener diode operates in reverse bias and exhibits a nearly constant breakdown voltage, making it useful for providing a stable reference voltage.
The document discusses the zener diode, including its construction, working principle, and applications. A zener diode operates in reverse breakdown to regulate voltage. It has a very thin, heavily doped depletion region which allows breakdown at low voltages. Zener diodes are used to provide stable reference voltages for applications like power supplies.
The zener diode is designed to operate in reverse bias and maintain a stable reference voltage within a circuit. It achieves this through a carefully controlled manufacturing process that heavily dopes the silicon pn junction with impurities, creating a very thin depletion region. This allows the zener diode to undergo breakdown at low reverse voltages, enabling it to function as a voltage regulator when placed in reverse bias within a circuit.
Best 3 Applications Involving in Zener Diode Working Functionalityelprocus
Zener diodes are normal PN junction diodes operating in a reverse biased condition. Working of the Zener diode is similar to a PN junction diode in forward biased condition, but the uniqueness lies in the fact that it can also conduct when it is connected in reverse bias above its threshold / breakdown voltage. These are among the basic types of diodes used frequently, apart from the normal diodes.
Zener diodes are designed to operate in reverse breakdown at a specific voltage. They maintain a stable reference voltage through the zener effect which causes a dramatic increase in current below around 6V. A zener diode can be used in a voltage regulator circuit with a series resistor to maintain a constant output voltage across a load despite variations in input voltage or load current. When operating, the zener diode is reverse biased and acts to clamp the voltage at its breakdown level.
This document outlines an experiment to understand how a zener diode can be used as a voltage regulator. It describes how zener diodes have a high doping level that allows them to maintain a constant voltage under reverse bias. The circuit uses a zener diode, resistors, potentiometer and battery to regulate the voltage. By varying the potentiometer, the voltage drop across the zener diode remains constant at its breakdown voltage. Voltage regulators are important in electronics to provide a steady voltage for circuits.
This document contains lecture notes on diode applications and types. It discusses topics like full wave and bridge rectifiers, power supply filters, diode clippers and clampers, zener diodes, varactor diodes, LEDs, photodiodes, and schottky diodes. It provides circuit diagrams and explanations of how each component works, along with example calculations for determining voltage, current, and resistance values.
The zener diode can be used as a voltage regulator. It has two operating conditions: forward bias and reverse bias. In reverse bias, the current remains constant for some voltage values due to minority charge carriers. If the voltage is further increased, the current reaches a maximum value at the reverse breakdown voltage. This sudden increase in current can be due to either the Zener effect or avalanche effect. The zener diode maintains a constant output voltage regardless of fluctuations in the input voltage by keeping the voltage drop across a series resistor equal to changes in the input voltage.
The document discusses the use of Zener diodes as voltage regulators. It begins by describing how Zener diodes allow current to flow in the reverse direction above a certain breakdown voltage. It then discusses different types of Zener diodes categorized by voltage, current, and power ratings. The document explains that Zener diodes can regulate an unsteady input voltage to provide a steady output voltage. It provides an example circuit diagram of a Zener diode regulating a 12V supply down to a steady 8V for a 100mA load. Measurements and component selections are described to illustrate how the Zener diode maintains a constant voltage across varying loads and minor input fluctuations.
This presentation introduces Zener diodes. It discusses that a Zener diode is a silicon pn junction designed to operate in reverse breakdown, maintaining a constant voltage even as current changes. The document examines Zener breakdown characteristics, showing how reverse current increases rapidly at the knee point where breakdown begins. It provides an example calculation of Zener impedance. Applications of Zener diodes discussed include waveform clipping, voltage regulation, and voltage shifting.
The document discusses diodes and their applications. It explains that diodes allow current to flow easily in one direction but block it in the other, acting like a one-way valve. It describes the basic diode characteristics and models. It then discusses how a p-n junction forms and how applying a voltage bias allows current to flow. Different types of diodes are also summarized, including power diodes, signal diodes, and Zener diodes. Two diode circuit applications - a clamp and stiff clamp - are explained briefly.
This document summarizes an experiment performed with a Zener diode. The students measured the voltage and current characteristics of the diode by varying the voltage in one circuit and the load resistance in another. They found the breakdown voltage of the diode experimentally and obtained a second characteristic curve by changing the load resistance. The document then describes the theoretical characteristics and functioning of a Zener diode, including its use as a voltage regulator.
The document discusses light emitting diodes (LEDs). It outlines the major characteristics required of light sources, including small size, minimum distortion/noise, emitting light at wavelengths where fiber has low losses, capable of signal modulation over a wide bandwidth, coupling sufficient optical power, narrow spectral width, and being stable, cheap and reliable. It describes the basic construction of an LED, which consists of a semiconductor diode chip encapsulated in a suitable lens. The document explains the operating principle of LEDs, where electrons recombine with holes at the PN junction, emitting photons of light rather than heat like ordinary diodes. It provides examples of LED applications like power indicators, blown fuse indicators, and light bulbs, noting advantages of LED
Zener diodes allow current to flow in both the forward and reverse directions. In the reverse direction, current only flows when the voltage exceeds the Zener voltage. Zener diodes can be used as voltage regulators by introducing them into a circuit driven by a current source. As the voltage increases past the Zener voltage, the diode draws excessive current from the supply to maintain a constant output voltage. Zener breakdown occurs through heavily doped regions near the contacts, allowing current at a lower voltage than normal avalanche breakdown.
1. ZENER DIODE and It’s Application
2. ZENER DIODE Zener diode are specifically designed to operate under reverse breakdown conditions. These diodes have a very accurate and specific reverse breakdown voltage. OR A Zener diode is a particular type of diode that, unlike a normal one, allows current to flow not only from its anode to its cathode, but also in the reverse direction, when the Zener voltage is reached.
3.Circuit Diagram the most basic Zener diode circuit consist of a single Zener diode and a resister.
The Zener diode provides the reference voltage.
A series resistor must be in place to limit the current into the diode otherwise a large amount of current would flow through it and it could be destroyed.
The document discusses the working principles of zener diodes. It explains that zener diodes are designed to operate in the reverse breakdown region, unlike standard rectifier diodes. There are two types of breakdown that can occur for a reverse biased p-n junction - zener breakdown and avalanche breakdown. Zener breakdown occurs at lower voltages between 2-8V and is used to regulate voltage. The zener diode maintains a constant voltage for changing currents, making it useful in voltage regulator circuits.
El diodo Zener es un tipo especial de diodo diseñado para funcionar en la zona de ruptura e implementado en reguladores de tensión para mantener una tensión constante entre sus terminales a pesar de variaciones en la tensión de entrada, la resistencia de carga o la temperatura. Fue inventado por Clarence Melvin Zener y mantiene una tensión constante cuando se polariza inversamente, distinguiéndose de los diodos de avalancha.
This document discusses the fundamentals of laser diodes, including:
1) Laser diodes use direct bandgap semiconductors where electron-hole recombination emits photons of light equal to the bandgap energy. Population inversion, needed for lasing, can be achieved through heavy doping of both p-type and n-type materials near the depletion layer.
2) Early laser diodes used homojunctions but now use double heterojunctions of GaAs for the active region surrounded by higher bandgap AlGaAs for better optical confinement.
3) Double heterojunction lasers have lower lasing thresholds than earlier designs due to reduced optical losses from improved carrier and light confinement, though
The document discusses the use of lasers in ophthalmology and refractive surgery. It describes different types of lasers including argon, diode, Nd:YAG, and excimer lasers. It explains how each laser is used for applications like retinal photocoagulation, iridotomy, trabeculoplasty, and refractive surgery procedures like PRK and LASIK. Key factors that determine laser tissue effects and goals of different laser treatments are also summarized.
This document discusses Zener diodes. It begins with an introduction to diodes in general and then focuses on Zener diodes. Key points covered include: the electric symbol and parameters of a Zener diode; the forward and reverse voltage-current characteristics; advantages like voltage regulation and disadvantages like power waste; circuit tips for using Zener diodes as voltage regulators; and references for further information. The document aims to provide an overview of Zener diodes, their characteristics and applications.
This document discusses the Schottky diode, a semiconductor diode with a low forward voltage drop and very fast switching speeds. It forms a metal-semiconductor junction, using a metal like molybdenum or platinum in contact with an N-type semiconductor like silicon. This creates a Schottky barrier and results in fast switching without the charge storage and recovery time of a conventional PN junction diode. Key advantages are voltage drops as low as 0.15V, no reverse recovery time, and operation at frequencies from MHz to GHz. Applications include rectification, switching, and protection circuits.
This document provides an overview of zener diodes, including their construction, working, and applications. It describes how zener diodes are constructed with heavy doping to reduce the breakdown voltage and have a thin depletion region. It explains that zener diodes work by operating in reverse breakdown at a specific, controlled voltage. Common applications include providing a stable reference voltage for power supplies and limiting voltage swings in AC applications.
PIN diode consists of heavily doped P and N regions separated by a wide intrinsic region. The wide intrinsic region makes the PIN diode suitable for attenuators, fast switches, photo detectors, and high voltage power electronics applications. PIN diode works as an ordinary PN junction diode up to 100 MHZ, above which it ceases rectification and behaves as a switch or variable resistor. In reverse bias it acts as a capacitor, while in forward bias it acts as a variable resistor whose value decreases with increasing voltage. PIN diodes are used in RF and dc controlled microwave switches, RF and variable attenuators, limiter circuits, photo detectors, and RF modulator circuits.
Basic electronics and electrical first year engineeringron181295
The document provides information on p-n junction diodes and their characteristics:
- A p-n junction is formed at the boundary between p-type and n-type semiconductor materials. When joined, electrons and holes diffuse across the junction forming a depletion region.
- Diodes can be forward or reverse biased by applying an external voltage. In forward bias, current flows through the majority carriers. In reverse bias, the depletion region widens preventing majority carrier flow, but some minority carrier current still flows.
- The V-I characteristics of a diode show regions of forward conduction, reverse saturation current, and breakdown. Key parameters are forward voltage drop, reverse breakdown voltage, and dynamic resistance.
The document discusses the physics of semiconductors including PN junction diodes and resistors. It covers semiconductor fundamentals like doping and intrinsic nature. It describes how doping materials like phosphorus or boron create N-type or P-type semiconductors. When an N-type and P-type material come into contact, a PN junction is formed with a depletion region and electric field. A PN junction acts as a switch that only allows current in one direction depending on whether it is forward or reverse biased.
This document provides information about a learning module on bread and pastry production for grades 7 and 8. It contains 4 lessons that cover key competencies including using tools and bakery equipment, performing measurements and calculations, maintaining tools and equipment, and practicing occupational health and safety procedures. The first lesson defines terms and identifies various baking tools and their uses, such as cake pans, biscuit cutters, mixing bowls, and measuring cups and spoons. It emphasizes the importance of preparing tools and equipment for their specific baking purposes.
The document discusses PIN diodes and varactor diodes. A PIN diode has a wide intrinsic semiconductor region between a p-type and n-type region, making it suitable for applications like attenuators and switches. It operates as a variable resistor at radio frequencies. A varactor diode provides a voltage-dependent variable capacitance and is used for electronic tuning and frequency multiplication. Both diodes have applications in radio frequency circuits due to their ability to dynamically control signal properties.
Here are the key points covered in the information sheet:
- Screwdrivers (standard/flat, Philips, stubby, Allen) are used to loosen or tighten screws of different head types.
- Hammers are used for driving or pulling out nails. Types include claw hammer, mallet, ballpeen hammer.
- Pliers (combination, side cutting, long nose) are used for cutting, twisting, bending wires and cables.
- Other tools include wire strippers, electrician's knife, portable electric drill, hacksaw.
- Electrical materials include convenience outlets, male plugs, lamp holders (flush, hanging, surface), switches (hanging, flush, surface)
The document discusses various basic hand tools used in electronics servicing. It describes screwdrivers like slotted and Phillips screwdrivers. Soldering tools discussed include soldering irons, soldering tool stands, and desoldering tools. Boring tools mentioned are mini-drills and portable electric drills. Cutting tools include utility knives and hacksaws. Auxiliary tools discussed are magnifying glasses and paint brushes. Electrical equipment defined are volt-ohm-milliammeters, oscilloscopes, and signal generators. The document concludes by asking the reader to classify different hand tools according to their specification.
This document provides an overview of special purpose diodes including zener diodes, optical diodes, and varactor diodes. It discusses zener diodes in detail, explaining their operation and characteristics such as the zener voltage-current relationship and temperature coefficient. Applications of zener diodes as voltage regulators and limiters are described. The document also covers light emitting diodes (LEDs) and photodiodes, explaining their basic operation, characteristics such as spectral output and radiation pattern, and common applications. Sample problems are included for zener diode and LED circuits.
Voltage regulation circuits like the zener diode and three-terminal regulators can maintain a constant output voltage despite fluctuations in load conditions or input voltage. A zener diode operates in reverse bias to regulate voltage at a specific breakdown voltage. A three-terminal voltage regulator integrated circuit provides precise voltage control with only a few external components and has built-in protections like overcurrent prevention. The adjustable three-terminal regulator uses a resistor network and reference voltage to set the output voltage.
A Zener diode is a semiconductor device designed to operate in reverse bias by taking advantage of the Zener effect. It can regulate voltage in a circuit by maintaining a constant voltage drop when the reverse bias voltage exceeds the Zener voltage. The Zener diode symbol is drawn with an arrow representing forward bias current. It has applications in voltage regulation, signal clamping, voltage references, and overvoltage protection.
Zener diodes are semiconductor devices designed to function in the reverse direction by allowing current to flow when a breakdown voltage is reached. They can regulate voltage in circuits and are used for applications like voltage regulation, signal clamping, voltage references, and overvoltage protection. Key specifications for Zener diodes include their breakdown voltage which can range from 2.4V to 1kV, and their maximum current rating. Circuits using Zener diodes provide advantages like low cost voltage stabilization but also have disadvantages like wasting electricity during voltage regulation.
Zener diodes are semiconductor devices designed to function in the reverse direction by allowing current to flow when a breakdown voltage is reached. They can regulate voltage in circuits and are used for applications like voltage regulation, signal clamping, voltage references, and overvoltage protection. Key specifications for Zener diodes include their breakdown voltage which can range from 2.4V to 1kV, and their maximum current rating. Circuits using Zener diodes provide advantages like low cost voltage stabilization, but disadvantages include wasting electricity during voltage cancellation and poorer regulation than transistors.
Zener diodes are diodes designed to operate in reverse bias mode to regulate voltage in a circuit. They have a breakdown voltage known as the Zener voltage that allows current to flow in reverse direction. Zener diodes are used for voltage regulation, signal clamping, voltage references, and overvoltage protection in circuits. Their advantages include low cost, ability to regulate and stabilize voltage, high performance, ability to control current flow, and wide availability. However, their disadvantages are higher power consumption compared to other regulators and poorer regulation ratio than transistors.
The Zener diode can regulate voltage by maintaining a constant reverse breakdown voltage. It does this by operating in reverse bias mode, where it exhibits a nearly constant voltage over a range of reverse currents. This makes it useful for voltage regulation, where connecting a Zener diode across an output can stabilize the voltage despite variations in input voltage or load current.
The document discusses different types of diodes, including Zener diodes, Schottky diodes, and tunnel diodes. It defines Zener diodes as diodes designed to operate in the reverse breakdown region and explains their use as voltage references. It also provides examples of calculating Zener impedance and the effects of temperature on Zener voltage. Schottky diodes are described as having low forward voltage drop and high efficiency but low reverse voltage rating. Tunnel diodes exhibit negative resistance due to quantum tunneling, which allows them to be used in oscillator circuits.
This document discusses different types of diodes, including their basic functions and applications. It begins with an overview of basic diodes and their current-voltage characteristics. It then focuses on special diodes like Zener diodes, which maintain a relatively constant voltage when operated in reverse breakdown. Other diodes discussed include varactor diodes, light-emitting diodes (LEDs), photodiodes, Schottky diodes, laser diodes, PIN diodes, current regulator diodes, step-recovery diodes, and tunnel diodes. Each type has a specialized function and is commonly used in applications like power regulation, displays, optical communications, and high-frequency switching.
The diode allows current to pass in one direction only. It is used as a rectifier in power supplies to convert alternating current (AC) to direct current (DC). The diode uses a single P-N junction made of semiconductor material. The zener diode can operate in reverse bias and maintains a stable voltage, making it useful for voltage regulation and reference circuits. Diodes come in different package styles and are identified by alphanumeric codes and cathode markings.
The diode allows current to pass in one direction only. It is used as a rectifier in power supplies to convert alternating current (AC) to direct current (DC). The diode uses a single P-N junction made of semiconductor material. The zener diode can operate in reverse bias and maintains a stable voltage, making it useful for voltage regulation in circuits. Diodes come in different package styles and are identified by alphanumeric codes and cathode markings.
Electrical Engineering is the Branch of Engineering. Electrical Engineering field requires an understanding of core areas including Thermal and Hydraulics Prime Movers, Analog Electronic Circuits, Network Analysis and Synthesis, DC Machines and Transformers, Digital Electronic Circuits, Fundamentals of Power Electronics, Control System Engineering, Engineering Electromagnetics, Microprocessor and Microcontroller. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus. Visit : https://ekeeda.com/streamdetails/stream/Electrical-and-Electronics-Engineering
A Zener diode operates in the reverse breakdown region with a sharp breakdown voltage. It is an ordinary P-N junction diode that is properly doped to have a very sharp and almost vertical breakdown. It is designed to operate exclusively under reverse bias conditions in the breakdown region without damage. The breakdown voltage can range from 2V to 800V depending on the doping level. When reverse biased, a small reverse saturation current flows until the breakdown voltage is reached, at which point the reverse current increases sharply. This breakdown voltage is called the Zener voltage and remains constant even as the Zener current increases considerably, allowing the Zener diode to be used for voltage regulation.
Bee Electronic microproject Roll No.41 to 44.pptxSwarajSalunkhe1
1. The report discusses the working of a Zener diode and how it can be used as a voltage regulator. It explains that a Zener diode allows current to flow in the reverse direction when the Zener voltage is reached.
2. The report includes the symbol of a Zener diode and provides a circuit diagram showing how a Zener diode can regulate voltage. It explains that the voltage across a Zener diode remains constant over a range of currents.
3. Resources on Zener diodes and voltage regulators are cited at the end to provide additional information on the topic.
The document introduces a group project presentation on Zener diodes. It defines a Zener diode as a type of diode that allows current to flow in both the forward and reverse directions when the reverse voltage exceeds the Zener voltage. It then lists the group members and provides information on the characteristics, basic circuit, applications, and use of Zener diodes as voltage regulators and limiters.
This document summarizes a seminar presentation on Zener diodes. It introduces Zener diodes as diodes that can operate continuously in reverse breakdown without damage due to heavy doping. It describes their symbolic representation and characteristics, including that they regulate voltage by maintaining a constant voltage even if current varies. Applications discussed include voltage regulation, use in power supplies, meter protection, and comparators.
Semiconductor
If a valence Electron acquires sufficient kinetic energy to break its covalent bond and fills the void created by a hole then a vacancy, or hole will be created in the covalent bond that released the electron
Hence there is a transfer of holes to the left and electrons to the right
Description of zener diode.
Know about the equivalent circuits.
Know about zener diode and how it works as voltage stabilizer.
see its advantages and also its disadvantages
Thanks in advance.
Diodes allow current to flow in only one direction. They have a small, constant voltage drop of about 0.7V when conducting electricity forward. Diodes do not conduct in reverse unless the reverse voltage exceeds a maximum breakdown value. There are two main types: signal diodes for small currents below 100mA, and rectifier diodes for larger currents used in power supplies to convert alternating current to direct current. Zener diodes are designed to conduct reliably in reverse at a specific breakdown voltage, making them useful for maintaining a fixed voltage in circuits.
This presentation discusses cognitive internet of vehicles (C-IoV). It provides a timeline of intelligent transportation systems and an overview of the layered architecture of C-IoV. It discusses security and privacy issues for C-IoV, including threats like eavesdropping, message alteration, and denial of service attacks. Recommendations are made for future research on C-IoV, including reducing latency, improving system performance, and addressing security and privacy challenges.
This certificate of completion was awarded to Fida Hasan by Professor Suzi Derbyshire, Deputy Vice-Chancellor of Learning and Teaching, for completing a series of courses through QUT Academic Development on topics related to learning and teaching foundations, student success, assessment and academic success in 2016.
This document summarizes research on positioning accuracy for cooperative intelligent transport systems. It discusses how GPS alone cannot satisfy the high-accuracy positioning needs of safety-critical applications in certain environments. New positioning algorithms are being developed that integrate GPS with other sensors and vehicle-to-vehicle communication using DSRC. Current research includes developing techniques for collaborative positioning based on radio range, range-rates, and non-radio ranges. Evaluation of collaborative positioning datasets shows improvements over standalone GPS/INS of up to 60% in positioning accuracy. Future work aims to improve DSRC observations and integration algorithms while incorporating additional sensors.
The document provides guidelines for writing a term paper, including recommendations for its structure, content, formatting, and citations. Key aspects that must be addressed are length (20-25 pages), structure (introduction, literature review, methodology, etc.), citation style, accuracy, and avoiding plagiarism. Recommendations are provided for each section, including the level of detail required for the methodology, presentation of results, discussion of limitations, and bibliography format. The guidelines aim to help students write a well-structured, scholarly term paper.
This document is a lecture slide on basic electrical circuits. It directs the reader to see examples 14.10, 14.17, and 14.18 from chapter 14 of the 10th edition of the book "Introductory Circuit Analysis" by Robert L. Boylestad for more information on circuit analysis. The slide provides a title and source but no additional content.
Este documento apresenta uma aula sobre circuitos elétricos básicos. Ele contém 17 slides com informações sobre o site www.fida.com.bd em cada um deles.
Este documento é uma apresentação sobre circuitos elétricos básicos contendo 35 slides que fornecem informações sobre o site www.fida.com.bd em cada uma delas.
Este slide de aula sobre circuitos elétricos básicos fornece exemplos de problemas de circuitos de capítulo 8 do livro "Análise de Circuitos Introdutória" de Robert L. Boylestad e lista problemas de atribuição sobre o assunto.
Este documento é uma apresentação sobre circuitos elétricos básicos que inclui links para o site www.fida.com.bd em várias linhas, uma referência a um livro sobre análise de circuitos e uma seção final de problemas de atribuição.
Este slide de palestra sobre circuitos elétricos básicos contém uma lista de links para o site www.fida.com.bd nas páginas 3 a 16, fornecendo recursos online sobre o tema.
This document is a lecture slide on basic electrical circuits. It lists the website www.fida.com.bd multiple times and references examples 9.3 and 9.12 from Chapter 9 of the 10th edition of the textbook "Introductory Circuit Analysis" by Robert L. Boylestad. It also mentions that problems will be assigned.
Este slide de palestra apresenta informações básicas sobre circuitos elétricos. Ele inclui dez links para o site www.fida.com.bd, possivelmente fornecendo recursos adicionais sobre o tema.
This document is a lecture slide on basic electrical circuits. It references examples 7.2 and 7.8 from Chapter 7 of the 10th edition of the textbook "Introductory Circuit Analysis" by Robert L. Boylestad. The slide directs students to see these examples and lists problems for an assignment on basic electrical circuits.
This lecture slide covers basic electrical circuits. It defines elements in series and notes their shared resistance. Examples are provided from Chapter 5 of the textbook "Introductory Circuit Analysis" by Robert L. Boylestad, including series circuits, voltage divider rule, and more. Further examples are given from Chapter 6 on Kirchhoff's laws and circuit analysis techniques. The slide concludes with assignment problems related to the circuit concepts.
This document discusses various methods for transmitting data over telephone and cable networks, including telephone networks using circuit switching, dial-up modems, digital subscriber line (DSL) technology, cable TV networks, and using cable TV networks for high-speed data transfer. Specific topics covered include components of telephone networks, signaling, services provided, modem standards, types of DSL technologies like ADSL and HDSL, hybrid fiber-coaxial cable networks, and DOCSIS cable modem standards. Diagrams and tables illustrate these various network architectures and technologies.
This document discusses different types of switched networks including circuit-switched, datagram, and virtual-circuit networks. It provides examples and diagrams to illustrate key characteristics of each type. The document also describes the structure of switches used in circuit-switched and packet-switched networks, comparing crossbar and multistage switch designs. Specific switching techniques like time-slot interchange, time-space-time, and banyan switches are examined.
This document provides information on bandwidth utilization techniques like multiplexing and spreading. It discusses different types of multiplexing including frequency-division multiplexing (FDM), wavelength-division multiplexing (WDM), synchronous time-division multiplexing (TDM), and statistical TDM. Examples are provided to illustrate how these techniques work and how to calculate key parameters like bandwidth, data rate, and duration when multiplexing multiple channels into a single link.
This document provides an introduction and overview of key topics in data communications and computer networks. It discusses five components of data communication, different types of data flow, how networks connect various devices and transfer data, common network topologies like bus, star and ring configurations, the development of the Internet and how it revolutionized information sharing, and the importance of protocols and standards in ensuring interoperability between different network technologies. The document includes diagrams and figures illustrating these network concepts.
This document provides an overview of error detection and correction techniques in digital communications. It discusses different types of errors that can occur like single-bit and burst errors. It explains how redundancy is used to detect and correct errors. Block coding techniques are described that divide messages into blocks and add redundant bits to create codewords. Linear block codes are introduced where the XOR of two codewords results in another valid codeword. Simple parity-check codes are discussed as a basic error detecting code using a single redundant bit. Examples are provided to illustrate concepts like minimum Hamming distance, error detection and correction capabilities of different codes.
This document discusses different types of transmission media, including guided and unguided media. Guided media includes twisted-pair cable, coaxial cable, and fiber-optic cable. Unguided or wireless media transports electromagnetic waves without a physical conductor and includes radio waves, microwaves, and infrared signals. The document contains diagrams, tables, and notes about each type of transmission medium and their usage and characteristics.
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1. LECTURE-6 (EEE-201)
Electronic Circuits-1
by
Khondokar Fida Hasan
www.fida.com.bd
2. Special Diodes:
Objectives
Describe the characteristics of a zener diode and analyze its operation
Explain how a zener is used in voltage regulation and limiting
Describe the varactor diode and its variable capacitance
characteristics
Discuss the operation and characteristics of LEDs and photodiodes
Discuss the basic characteristics of the current regulator diode, the
pin diode, the step-recovery diode, the tunnel diode, and the laser
diode.
www.fida.com.bd
3. Introduction
The basic function of zener diode is to maintain a specific voltage
across its terminals within given limits of line or load change. Typically
it is used for providing a stable reference voltage for use in power
supplies and other equipment.
RLoad
This particular zener circuit will work to maintain 10 V across the load.
www.fida.com.bd
5. Zener Diodes – Operating Range
A zener diode is much like a
normal diode, the exception
being is that it is placed in
the circuit in reverse bias
and operates in reverse
breakdown. This typical
characteristic curve
illustrates the operating
range for a zener. Note that
its forward characteristics
are just like a normal diode.
Operating range
www.fida.com.bd
6. Zener Diodes – Regulation Ranges
The zener diode’s breakdown Zener zone Diode zone
characteristics are determined by
the doping process. Low voltage
zeners (>5V), operate in the zener
breakdown range. Those designed
to operate <5 V operate mostly in
avalanche breakdown range.
Zeners are available with voltage
breakdowns of 1.8 V to 200 V.
Avalanche
zone
5V.
This curve illustrates the minimum and maximum
ranges of current operation that the zener can
effectively maintain its voltage.
www.fida.com.bd
7. Zener Diodes – Breakdown
Characteristics
Note very small reverse
current (before “knee”).
Breakdown occurs @
knee.
Breakdown
Characteristics:
• VZ remains near constant
• VZ provides:
-Reference voltage
-Voltage regulation
• IZ escalates rapidly
• IZ MAX is achieved quickly
• Exceeding IZ MAX is fatal
www.fida.com.bd
8. Zener Diodes – Voltage Regulation
Regulation occurs between:
VZK - knee voltage
to
VZM - Imax
www.fida.com.bd
9. Zener Diodes – Equivalent Circuit
• Ideal Zener exhibits a
constant voltage,
regardless of current
draw.
• Ideal Zener exhibits no
resistance
characteristics.
www.fida.com.bd
10. Zener Diodes – Equivalent Circuit
• Zener exhibits a near
constant voltage, varied
by current draw
through the series
resistance ZZ.
• As Iz increases, Vz also
increases.
www.fida.com.bd
11. Zener Diodes – Characteristic Curve
• ∆Vz results from ∆Iz.
• ∆Iz thru Zz produce
this.
See Ex. 3-2
www.fida.com.bd
12. Zener Diodes
Zener diodes have given characteristics such as;
• Temperature coefficients – describes the % ∆Vz for ∆Temp (0C)
∆Vz = Vz x T0C x ∆T %/oC
See Ex.3-3 (∆Vz)
• Power ratings – the zener incurs power dissipation based on Iz and Zz P = I2Z
Power derating factor specifies the reduced power rating for device operating
temperatures in excess of the “rated maximum temperature”.
PD(derated) = PD(max) – (mW/0C)∆T mW
The data sheet provides this information. See Ex.3-4 (%/oC)
www.fida.com.bd
13. Zener Diode –
Data Sheet
• Power ratings
• Temperature
ratings
• Vz nominal
• Impedance
• Power derating
curves
• Temperature
coefficients
• ∆Zz - Zener
impedance
www.fida.com.bd
14. Zener Diode - Applications
Regulation
In this simple illustration of zener regulation circuit, the zener diode will
“adjust” its impedance based on varying input voltages. Zener current will
increase or decrease directly with voltage input changes. The zener current, Iz,
will vary to maintain a constant Vz.
Note: The zener has a finite range of current operation.
VZener
remains
constant
www.fida.com.bd
15. Zener Diode - Applications
Regulation
In this simple illustration of zener regulation circuit, the zener diode will
“adjust” its impedance based on varying input voltages and loads (R L) to be
able to maintain its designated zener voltage. Zener current will increase or
decrease directly with voltage input changes. The zener current will increase
or decrease inversely with varying loads. Again, the zener has a finite range
of operation.
VZener
remains
constant
See Ex. 3-5
www.fida.com.bd
Acrobat Document
16. Zener Limiting
Zener diodes can used for limiting just as normal diodes. Recall in
previous chapter studies about limiters. The difference to consider for
a zener limiter is its zener breakdown characteristics.
www.fida.com.bd See Ex.3-8
17. Analysis of Zener Diode as a voltage regulator
When,
www.fida.com.bd
26. Varactor Diodes
A varactor diode is best explained as a variable capacitor. Think of the
depletion region as a variable dielectric. The diode is placed in reverse bias.
The dielectric is “adjusted” by reverse bias voltage changes.
www.fida.com.bd
27. Varactor Diodes
The varactor diode can be useful in filter circuits as the adjustable component for
resonance frequency selection.
Varactor
Bias adjust
www.fida.com.bd
28. Varactor Diodes
Capacitance Tolerance Range
- This is the equivalent of the value tolerance range of a resistor.
ie: 1N5148 – Nominal value = 47pFd
- Tolerance range is 42.3pFd to 51.7pFd
Tuning Ratio (TR) or (Capacitance Ratio)
- Refers to Rangeability (value @ Bias Vmax vs Bias Vmin)
- Vmin is 4V bias (C4) (for the 1N5139, C4 = 6.8pFd)
- Vmax is 60V bias (C60) (for the 1n5139, C60 = 2.3pFd)
For the 1N5139, TR = 2.9
Quality Factor (Q) describes energy loss in the device. High Q desireable)
Temperature Coefficient - ∆Capacitance vs ∆Temp
See pg.127
Acrobat Document www.fida.com.bd See Ex.3-9
29. Resonant Band-pass Filter w/ Varactor Diode
Parallel Resonant Tank
Series Resonant
31.6V
Tank
Varactor
VR = 2.85 to 28.7V
VBIAS = 2.9V to 29V
CVaractor = 17pF to 55pF
Varactor Bias
Resonant Frequency Range:
fr = 679kHz to 1.22MHz. www.fida.com.bd See Related Problem pg.130
30. Optical Diodes
The light-emitting diode (LED) emits photons as visible light.
Its purpose is for indication and other intelligible displays.
Various impurities are added during the doping process to
vary the color output.
www.fida.com.bd
31. Optical Diodes
Electroluminescence, the process of emitting
photons from a parent material (substrate), is
the basis for LEDs.
Colors result from the choice of substrate
material and the resulting wavelength;
Todays LEDs (green,red, yellow) are based on
indium gallium aluminum phosphide
Blue uses silicon carbide or gallium nitride
IR (infrared) – GaAs (gallium arsenide)
A strong +bias encourages
LED Biasing: 1.2V to 3.2V is typical. conduction-band electrons
in the N-material to leap the
Note: Some newer LED’s run at higher voltages junction and recombine
and emit immense light energy. Applications: with available holes
Traffic signals releasing light and heat.
Outdoor video screens
www.fida.com.bd
Runway markers
32. LED – Spectral Curves
Note the wavelengths of the various
colors and infrared.
Note lead designations to the right.
www.fida.com.bd
35. Optical Diodes
The seven segment display is an example of LEDs use for display of
decimal digits.
www.fida.com.bd Acrobat Document
See “Light Emitting Diodes.pdf”
36. Photodiodes
Unlike LED’s, photodiodes receive light rather than produce light. The
photodiode varies it’s current in response to the amount of light that
strikes it. It is placed in the circuit in reverse bias. As with most diodes, no
current flows when in reverse bias, but when light strikes the exposed
junction through a tiny window, reverse current increases proportional to
light intensity (irradiance).
Note: Photodiodes all
exhibit a “reverse
leakage current” which
appears as an inverse
variable resistance.
Irradiance causes the
device to exhibit a
reduction in the
variable resistance
characteristic.
www.fida.com.bd
40. Other Diode
Types
Current regulator diodes
(constant current diodes)
keep a constant current
value over a specified
range of forward bias
voltages ranging from
about 1.5 V to 6 V. Operating Range
This device exhibits very
high impedances.
www.fida.com.bd
41. Other Diode Types
The Schottky diode’s (hot-carrier diodes) significant characteristic is
its fast switching speed. This is useful for high frequencies and digital
applications. It is not a typical diode in that it does not have a p-n
junction. Instead, it consists of a lightly-doped n-material and
heavily-doped (conduction-band electrons) metal bounded together.
Response is very quick…high speed digital communications.
Lightly doped Heavily doped (conduction-
band electrons)
www.fida.com.bd
42. Other Diode Types
The pin diode is also used in mostly microwave frequency applications. Its
variable forward series resistance characteristic is used for attenuation,
modulation, and switching. In reverse bias it exhibits a nearly constant
capacitance. Also used in attentuators.
Current-controlled
Fixed Capacitance Resistance
www.fida.com.bd
43. Other Diode Types
The step-recovery diode is also used for fast switching
applications. This is achieved by reduced doping near the
junction. The diode recovers very quickly, making it useful in
high-frequency (VHF) applications.
www.fida.com.bd
44. Other Diode Types
The tunnel diode exhibits negative resistance. It will actually conduct well
with low forward bias. With further increases in bias it reaches the
negative resistance range where current will actually go down. This is
achieved by heavily-doped p and n materials that create a very thin
depletion region which permits electrons to “tunnel” thru the barrier
region.
Tank circuits oscillate but “die out” due to
the internal resistance. A tunnel diode will
provide “negative resistance” that
overcomes the loses and maintains the
oscillations.
Germanium or Gallium
www.fida.com.bd
45. Tunnel Diodes
Tank circuits oscillate but “die out” due to the internal resistance. A
tunnel diode will provide “negative resistance” that overcomes the
loses and maintains the oscillations.
www.fida.com.bd
46. Other Diode Types
The laser diode (light amplification by stimulated emission of radiation)
produces a monochromatic (single color) “coherent” light. Laser diodes
in conjunction with photodiodes are used to retrieve data from compact
discs.
Forward bias the diode and electrons move thru the junction,
recombination occurs (as ordinary). Recombinations result in
photon release, causing a chain reaction of releases and
avalanching photons which form an intense laser beam.
www.fida.com.bd
47. Troubleshooting
Although precise power supplies typically use IC type regulators, zener
diodes can be used alone as a voltage regulator. As with all
troubleshooting techniques we must know what is normal.
A properly functioning zener will work to maintain the output voltage
within certain limits despite changes in load.
www.fida.com.bd
48. Troubleshooting
With an open zener diode, the full unregulated voltage will be
present at the output without a load. In some cases with full or
partial loading an open zener could remain undetected.
www.fida.com.bd
49. Troubleshooting
With excessive zener impedance the voltage would be higher than normal
but less than the full unregulated output.
www.fida.com.bd
50. Summary
The zener diode operates in reverse breakdown.
A zener diode maintains a nearly constant voltage across its terminals
over a specified range of currents.
Line regulation is the maintenance of a specific voltage with changing
input voltages.
Load regulation is the maintenance of a specific voltage for different
loads.
There are other diode types used for specific RF purposes such as
varactor diodes (variable capacitance), Schottky diodes (high speed
switching), and PIN diodes (microwave attenuation and switching).
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51. Summary
Light emitting diodes (LED) emit either infrared or visible light when
forward-biased.
Photodiodes exhibit an increase in reverse current with light
intensity.
The laser diode emits a monochromatic light
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