The function of the diode is to regulate the voltage at a particular current. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get an original essay1. Small signal diode It is a small device with disproportionate characteristics and its applications are mainly in high frequency and very low current devices such as radios and televisions, etc. To protect the diode from contamination, it is wrapped in a glass, so it is also called Glass Passivated Diode widely used as 1N4148.2.2. Large Signal Diode These diodes have a large PN junction layer. Thus, the transformation of AC voltages into DC is unlimited. This also increases the current forward capacitance and reverse blocking voltage. These important signals will also disrupt the functional point. For this reason it is not suitable for high frequency applications.3. Zener Diode It is a passive element which operates according to the Zener breakdown principle. First produced by Clarence Zener in 1934. It is similar to a normal diode in the forward direction, it also allows current in the reverse direction when the applied voltage reaches the breakdown voltage. It is designed to prevent other semiconductor devices from momentary voltage pulses. It acts as a voltage regulator.4. Light Emitting Diode (LED)These diodes convert electrical energy into light energy. The first production began in 1968. It undergoes an electroluminescence process in which holes and electrons are recombined to produce energy in the form of light under forward polarization conditions.5. Constant Current Diodes They are also known as current regulating diode or constant current diode or current limiting diode or connected to diode6. Schottky diode In this type of diode, the junction is formed by bringing the semiconductor material into contact with metal. As a result, the forward voltage drop is reduced to a minimum. The semiconductor material is N-type silicon which acts as anode and the metal acts as cathode whose materials are chromium, platinum, tungsten, etc.7. Shockley diode This is the invention of the first four-layer semiconductor devices. It is also called PNPN diode. This is equivalent to a thyristor without a gate terminal, meaning the gate terminal is disconnected. Since there are no trigger inputs, the only way the diode will conduct is to provide a forward voltage.8. Step Recovery Diodes They are also called breakable diode or charge storage diode. This is a special type of diodes which stores the charge of a positive pulse and uses sinusoidal signals in the negative pulse. The rise time of the current pulse is equal to the latching time. Due to this phenomenon, it has speed recovery pulses.9. Tunnel diode It is used as a high-speed switch, in the nanosecond range. Due to the tunnel effect, it operates very quickly in the microwave frequency region. This is a two-terminal device in which the dopant concentration is too high.10. Varactor Diode These are also known as Varicap diodes. It acts as a variable capacitor. Operations are performed primarily in a reverse bias state only. These diodes are very famous because of their ability to change the capacitance ranges in the circuit in the presence of a constant voltage flow. APPLICATIONS OF DIODE VARACTORSa. Voltage controlled capacitors.b. Voltage controlled oscillators.c. Parametric amplifiers.d. Multipliers offrequency.e. FM transmitters and phase-locked loops in radios, televisions and cell phones.11. Laser diode Similar to LED in which the active region is formed by a pn junction. Electrically, the laser diode is a pin diode in which the active region is in the intrinsic region. Used in fiber optic communications, barcode readers, laser pointers, CD/DVD/Blu-ray reading and recording, laser printing.LASER DIODE TYPES:a. Double heterostructure laser: free electrons and holes available simultaneously in the region.b. Quantum Well Lasers: Lasers having more than one quantum well are called multiple quantum well lasers.c. Quantum CascadeLasers: These are heterojunction lasers that enable lasing action at relatively long wavelengths. Separately confined heterostructure lasers: To compensate for the thin layer problem in quantum lasers, we opt for separately confined heterostructure lasers. Distributed Bragg reflector lasers: These can be edge-emitting lasers or VCSELS.12. Transient Voltage Suppression DiodeIn semiconductor devices, state voltage transients will occur due to the sudden change of the state. They will damage the output response of the device. To overcome this problem, voltage suppression diodes are used. The operation of the voltage suppression diode is similar to the operation of the Zener diode.13. Gold doped diodes In these diodes, gold is used as a dopant. These diodes are faster than other diodes. In these diodes, the leakage current in reverse bias condition is also less. Even at higher voltage drop, this allows the diode to operate within signal frequencies. In these diodes, gold contributes to faster recombination of minority carriers.14. Super Barrier Diodes This is a rectifier diode having low forward voltage drop like Schottky diode with surge handling capability and low reverse leakage current like pn junction diode. It was designed for high power, fast switching and low loss applications. Super barrier rectifiers are the new generation rectifiers with low forward voltage compared to Schottky diode15. Peltier diode In this type of diode, at the junction of the two materials of a semiconductor, it generates heat which flows from one terminal to the other. This flow is in only one direction which is equal to the direction of current flow.16. Crystal Diode It is also known as cat's whisker, which is a type of point contact diode. Its operation depends on the contact pressure between the semiconductor crystal and the point.APPLICATIONS OF CRYSTAL DIODESa. Crystal diode rectifierb. Crystal diode detector. Crystal17 radio receiver. Avalanche diode This is a passive element that operates on the principle of avalanche breakdown. It works in reverse bias condition. This results in large currents due to the ionization produced by the pn junction during a reverse bias condition. THE AVALANCHE DIODE USES A. RF Noise Generation: It acts as an RF source for antenna analyzer bridges and also as a white noise generator. Used in radio equipment as well as hardware random number generators.b. Microwave frequency generation: In this, the diode acts as a negative resistance device.c. Single Photon Avalanche Detector: These are high gain photon detectors used in light level applications.18. Silicon controlled rectifier It consists of three terminals: the anode, the cathode and agrid. This is almost equal to the Shockley diode. As the name suggests, it is mainly used for control purposes when small voltages are applied in the circuit.19. Vacuum diodes Vacuum diodes consist of two electrodes which act as an anode and cathode. The cathode is made of tungsten which emits electrons towards the anode. The flow of electrons will always be from the cathode to the anode only. It therefore acts as a switch.20. PIN Diode The improved version of the normal PN junction diode results in the PIN diode. In the case of the PIN diode, doping is not necessary. Intrinsic material means that material that does not have charge carriers is inserted between the P and N regions, which increases the surface area of ​​the depletion layer. APPLICATIONS OF PIN DIODES: a. RF Switches: Pin diode is used for both signal and component selection. For example, pin diodes act as range switching inductors in low phase noise oscillators.b. Attenuators: It is used as bridge and shunt resistor in bridge-Tc attenuator Photodetectors: It detects X-ray and gamma-ray photons.21. Point Contact Devices A gold or tungsten wire is used as a contact point to produce a PN junction region by passing a high electric current through it. A small PN junction region is produced around the edge of the wire which is connected to the metal plate.22. Gunn Diode: The Gunn diode is manufactured with a nmaterial type semiconductor only. The depletion region of two N-type materials is very thin. As the voltage increases in the circuit, the current also increases. After a certain voltage level, the current will decrease exponentially, which presents a negative differential resistance. Discuss, illustrate, and derive the associated equations of various rectifier circuits. A widely used application of this feature and of diodes in general is the conversion of alternating voltage (AC) to direct voltage (DC). In other words, rectification. But small signal diodes can also be used as rectifiers in rectifiers or low-power, low-current (less than 1 amp) applications, but where larger forward bias currents or reverse bias blocking voltages more high are involved, the PN junction of a small signal diode would eventually overheat and melt, so larger, more robust power diodes are used instead. The power semiconductor diode, known simply as a power diode, has a much larger PN junction area compared to its smaller signal diode cousin, resulting in a high forward current capability ranging up to several hundred amps (KA) and a reverse blocking voltage of up to several thousand volts (KV). Since the power diode has a large PN junction, it is not suitable for high-frequency applications above 1 MHz, but special and expensive high-frequency, high-current diodes are available. For high frequency rectifier applications, Schottky diodes are typically used due to their short reverse recovery time and low voltage drop in their forward biased condition. Power diodes provide uncontrolled power rectification and are used in applications such as battery charging and DC power supplies as well as AC rectifiers and inverters. Due to their high current and voltage characteristics, they can also be used as freewheeling diodes and snubber networks. The power diodes aredesigned to have a forward “ON” resistance of fractions of an Ohm while their reverse blocking resistance is in the order of mega-Ohms. range. Some of the higher value power diodes are designed to be "stud mounted" on heat sinks, reducing their thermal resistance to between 0.1 and 1°C/Watt. If an alternating voltage is applied across a power diode, during the positive half cycle the diode will conduct the passage. current and during the negative half cycle the diode will not conduct, blocking current flow. Then the conduction through the power diode only occurs during the positive half cycle and is therefore unidirectional, i.e. DC, as shown. Power Diode Rectifier Power diodes can be used individually as above or connected together to produce a variety of rectifier circuits such as "half wave", "full wave" or as a "bridge rectifier". Each type of rectifier circuit can be classified as uncontrolled, semi-controlled, or fully controlled: an uncontrolled rectifier uses only power diodes, a fully controlled rectifier uses thyristors (SCR), and a semi-controlled rectifier is a mixture of diodes and thyristors. Half-Wave Rectification A rectifier is a circuit that converts alternating current (AC) input power to direct current (DC) output power. The input power supply may be a single-phase or multi-phase supply, the simplest of all rectifier circuits being that of the half-wave rectifier.A. Half-wave rectifier circuit The current on the DC side of the circuit flows in only one direction, making the circuit unidirectional. As the load resistor receives from the diode a positive half of the waveform, zero volts, a positive half of the waveform, zero volts, etc., the value of this irregular voltage would be equal to a DC voltage equivalent of 0.318 x Vmax. of the input sine waveform or 0.45 x Vrms of the input sine waveform. Then the equivalent DC voltage, VDC across the load resistor, is calculated as follows. Where Vmax is the maximum or peak voltage value of the AC sinusoidal power supply, and VS is the RMS (Root Mean Squared) value of the power supply.B. Half-Wave Rectifier with SmoothingCapacitorWhen rectification is used to provide direct voltage (DC) power from an alternating (AC) source, the amount of ripple voltage can be further reduced by using higher value capacitors , but there are limitations in both cost and size for smoothing types. capacitors used. In a full-wave rectifier circuit, two diodes are now used, one for each half of the cycle. A multi-winding transformer is used whose secondary winding is divided equally into two halves with a common center tap connection (C). This configuration causes each diode to conduct in turn when its anode terminal is positive with respect to the center point of transformer C, producing an output during the two half cycles, twice that of the half-wave rectifier, so that it is 100% effective, as shown below. . Full-wave rectifier circuit The diode bridge rectifier The full-wave rectifier circuit consists of two power diodes connected to a single load resistor (RL), each diode in turn responsible for supplying current to the load. When point A of the transformer is positive with respect to point C, diode D1 conducts in the forward direction as indicated by the arrows. As the spaces between each half-wave developed by each diode are now filled by the other diode, the average DC output voltage at theterminals of the load resistor is now twice that of the simple half-wave rectifier circuit and is approximately 0.637 V maximum of the peak voltage, assuming no losses. Where: VMAX is the maximum peak value in the secondary winding half and VRMS is the RMS value. The Full-Wave Bridge RectifierAnother type of circuit that produces the same output waveform as the full-wave rectifier circuit above is that of the full-wave bridge rectifier. Bridge rectifier. This type of single-phase rectifier uses four individual rectifier diodes connected in a closed-loop "bridge" configuration to produce the desired output. The four diodes labeled D1 through D4 are arranged in "series pairs" with only two diodes conducting current during each half cycle. During the positive half cycle of the power supply, diodes D1 and D2 conduct in series while diodes D3 and D4 are reverse biased and current flows through the load as shown below. The positive half-cycle During the negative half-cycle of the power supply, diodes D3 and D4 conduct in series, but diodes D1 and D2 turn off because they are now reverse biased. The current flowing through the load is in the same direction as before. The negative half-cycle As the current flowing through the load is unidirectional, the voltage developed across the load is also unidirectional, the same as for the previous two-diode full-wave rectifier, hence the average DC voltage across the load is 0.637 Vmax. Full-wave rectifier with smoothing capacitor The smoothing capacitor converts the full-wave ripple output of the rectifier into a smoother DC output voltage. If we now run the Partsim simulation circuit with different values ​​of smoothing capacitor installed, we can see the effect it has on the rectified output waveform, as shown. Discuss the block diagram of a power supply. You can illustrate it and the corresponding waveforms. As shown in View B of Figure 4-1, the first section is the TRANSFORMER. The transformer increases or decreases the input line voltage and isolates the power supply from the power line. The RECTIFIER section converts the AC input signal into a pulsating DC current. However, as you progress through this chapter, you will learn that pulsed DC is not desirable. For this reason, a FILTER section is used to convert pulsating DC current into a purer and more desirable DC voltage form. The final section, the REGULATOR, does exactly what its name suggests. It maintains the output of the power supply at a constant level despite significant changes in load current or input line voltages. Now that you know what each section does, let's trace an AC signal through the power supply. At this point you should see how this signal is changed in each section of the power supply. Later in the chapter you will see how these changes occur. In View B of Figure 4-1, an input signal of 115 volts AC is applied to the primary of the transformer. The transformer is a step-up transformer with a transformation ratio of 1:3. You can calculate the output of this transformer by multiplying the input voltage by the ratio of turns in the primary to the ratio of turns in the secondary; therefore, 115 volts ac3 = 345 volts ac (peak to peak) at the output. Since each diode in the rectifier section conducts 180 degrees of the 360 ​​degrees of input, the output of the rectifier will be half that, or about 173 volts of pulsating direct current. The filter section, a network of resistors,capacitors or inductors, controls the rise and fall time of the variable signal; therefore, the signal remains at a more constant DC level. You will see the filtering process more clearly in the discussion of actual filter circuits. The filter output is a 110 volt DC signal, with AC ripple on DC. The reason for the lower voltage (medium voltage) will be explained later in this chapter. The regulator maintains its output at a constant level of 110 volts DC, which is used by electronic equipment (more commonly called load). State other applications of a diode Applications of Diodes Although they are only two-pin semiconductor devices, there are a number of applications of diodes that are vital in modern electronics. Diodes are known for allowing current to only move in one direction through the component. This allows a diode to act like a one-way valve, keeping signals where they need to be or routing them around components. While diodes only pass current in one direction, each type of diode acts differently, making diodes a number of useful applications. Some of the typical applications for diodes include: • Rectifying a voltage, such as transforming AC to DC voltages • Isolating signals from a power supply • Voltage reference • Controlling the size of a signal • Mixing signals • Sensing signals • Lighting • Power Conversion Laser Diodes One important application of diodes is to convert alternating current into direct current. A single diode or four diodes can be used to transform the 110 V household supply to DC by forming a half-wave (single diodes) or full-wave (four diodes) rectifier. To do this, a diode only allows half of the alternating waveform to pass. When this voltage pulse is used to charge a capacitor, the output voltage appears to be a constant DC voltage with a small voltage ripple. Signal Demodulation The most common use for diodes is to remove the negative component of an AC signal so that it can be used more easily with electronics. Since the negative part of an AC waveform is usually the same as the positive half, very little information is actually lost during this process. Signal demodulation is commonly used in radios as part of the filtering system to help extract the radio signal from the carrier wave. Keep in mind: this is just a sample. Get a personalized article from our expert writers now. Get a Personalized Essay on Surge Protectors Diodes also work well as protective devices for sensitive electronic components. When used as voltage protection devices, diodes do not conduct under normal operating conditions but will immediately short any high voltage spike to ground where it cannot damage an integrated circuit. Specialized diodes called transient voltage suppressors are designed specifically for surge protection and can handle very large power surges for short periods of time, typical characteristics of a voltage spike or electrical shock, which would normally damage the components and shorten the life of an electronic product. Current Steering The basic application of diodes is to direct current and ensure that it flows only in the right direction. An area where the current driving capability of diodes is put to good use.