The function of the diode is to regulate the voltage to a particular current. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay1. Small signal diode It is a small device with disproportionate characteristics and whose applications mainly concern high frequency and very low current devices such as radios, televisions, etc. To protect the diode from contamination it is wrapped by glass, so it is also called as widely used glass passivated diode as 1N4148.2.2. Large Signal Diode These diodes have a large PN junction layer. Therefore the transformation of AC voltages to DC is unlimited. This also increases the forward current capability and reverse blocking voltage. These large signals also interrupt the functional point. For this reason it is not suitable for high frequency applications.3. Zener diode It is a passive element that works on the principle of zener breakdown. First produced by Clarence Zener in 1934. It is similar to the ordinary 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. Works as a voltage regulator.4. Light-emitting diodes (LEDs) 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 It is also known as current regulating diode or constant current diode or current limiting diode or connected diode6. Schottky diode In this type of diode the junction is formed by bringing the semiconductor material into contact with the metal. For this reason the forward voltage drop is reduced to min. 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 It was the invention of the first semiconductor devices with four layers. It is also called PNPN diode. It is the same as a thyristor without gate terminal, which means the gate terminal is disconnected. Since there are no trigger inputs, the only way the diode can conduct is by supplying forward voltage.8. Step recovery diodes It is also called snap-off diode or charge storage diode. These are the special type of diodes that store the charge from the positive pulse and use it in the negative pulse of sinusoidal signals. The rise time of the current pulse is equal to the snap time. Due to this phenomenon it has speed recovery impulses.9. Tunnel diode It is used as a high-speed switch, of the order of nanoseconds. Due to the tunneling effect, it works very fast in the microwave frequency region. It is a two-terminal device in which the concentration of dopants is too high.10. Varactor Diode These are also known as Varicap diodes. It works like the variable capacitor. Operations are mainly performed only in the reverse bias state. These diodes are very famous for their ability to change the capacitance ranges within the circuit in the presence of a constant voltage flow.VARACTOR DIODE APPLICATIONS. Voltage controlled capacitors.b. Voltage controlled oscillators.c. Parametric amplifiers.d. Frequency multipliers.e. FM transmitters and phase-locked circuits in radios, televisions and cell phones.11. Laser diode Similar to LED where the active region is formed by the pn junction. Electrically theLaser diode is a pin diode in which the active region is located in the intrinsic region. Used in fiber optic communications, barcode readers, laser pointers, CD/DVD/Blu-ray reading and recording, laser printing.TYPES OF LASER DIODES:a. Double heterostructure laser: free electrons and holes available simultaneously in the region.b. Quantum Well Lasers: Lasers that have more than one quantum well are called multi quantum well lasers.c. Cascade QuantumLasers: These are heterojunction lasers that allow laser action at relatively long wavelengths.d. Separately confined heterostructure laser: To compensate for the thin layer problem in quantum lasers we use separately confined heterostructure lasers. Distributed Bragg reflector lasers: These can be edge-emitting lasers or VCSELS.12. Transient Voltage Suppression Diode In semiconductor devices due to sudden change in state voltage transients will occur. 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 lower. Even with a higher voltage drop it allows the diode to operate in the signal frequencies. In these diodes gold contributes to faster recombination of minority carriers.14. Super Barrier Diodes This is a rectifier diode with low forward voltage drop as a Schottky diode with surge handling capability and low reverse leakage current as a pn junction diode. It was designed for high power, fast switching and low loss applications. Super barrier rectifiers are the next generation rectifiers with low forward voltage compared to the Schottky15 diode. Peltier diode In this type of diode, heat is generated at the junction of two semiconductor materials and flows from one terminal to the other. This flow occurs in a single direction which is equal to the direction of current flow.16. Crystal diode Also known as cat's whisker, it is a type of point contact diode. Its operation depends on the contact pressure between the semiconductor crystal and the point. CRYSTAL DIODE APPLICATIONS. Crystal diode rectifierb. Crystal diode detectorc. Crystal radio receiver17. Avalanche diode This is a passive element that works on the principle of avalanche breakdown. Works under reverse bias conditions. Large currents result due to the ionization produced by the pn junction during the reverse bias condition. USE OF THE AVALANCHE DIODea. RF Noise Generation: Serves as a source of RF for antenna analyzer bridges and also as white noise generators. Used in radio equipment and also in hardware random number generators.b. Generation of microwave frequencies: 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 Consists of three terminals: anode, cathode and gate. It is almost the same as the Shockley diode. As the name indicates, it is mainly used for control purposes when small voltages are applied in the circuit.19. Vacuum diodes Vacuum diodes consist of two electrodes that act as an anode and a cathode. The cathode is made of tungsten which emits electrons in the direction of the anode. The flow of electrons will always occur only from the cathodeto the anode. So it acts like a switch.20. PIN Diode The improved version of the normal PN junction diode provides the PIN diode. In the PIN the doping of the diodes is not necessary. Intrinsic material means that material which has no charge carriers is sandwiched between the P and N regions which increase the area of ​​the depletion layer.PIN DIODE APPLICATIONS:a. Rf Switches: The 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 attenuator-Tc Photodetectors: Detects X-ray and gamma ray photons.21. Point Contact Devices A gold or tungsten wire is used to act as a point contact to produce a PN junction region by passing a high electrical current through it. A small PN junction region is produced around the edge of the wire that is connected to the metal plate.22. Gunn Diode: Gunn diode is manufactured from n-type semiconductor material only. The depletion region of two N-type materials is very thin. As the voltage in the circuit increases, the current also increases. After a certain voltage level the current will decrease exponentially, so this presents the negative differential resistance. Discuss, illustrate and derive the related equations of various rectifier circuits. A widely used application of this feature and of diodes in general is in the conversion of an alternating voltage (AC) to a direct voltage (DC). In other words, rectification. But small-signal diodes can also be used as rectifiers or low-power, low-current applications (less than 1 A), but where larger forward bias currents or higher reverse bias blocking voltages are involved, the PN La junction of a small signal diode would eventually overheat and melt, so larger, more robust power diodes are used. The semiconductor power diode, known simply as the power diode, has a much larger PN junction area than its smaller signal diode cousin, resulting in a high forward current capability of up to several hundred A ( KA) and a reverse blocking voltage of up to several thousand volts (KV). Because the power diode has a large PN junction, it is not suitable for high-frequency applications above 1 MHz, but special, expensive high-frequency, high-current diodes are available. For high frequency rectifier applications, Schottky diodes are generally used due to their short reverse recovery time and low voltage drop in their forward bias 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. Power diodes are designed to have a forward "ON" resistance of fractions of ohms while their reverse blocking resistance is in the true mega-Ohm range. Some of the higher rated power diodes are designed to be "pin mounted" on heat sinks reducing their thermal resistance to between 0.1 and 1oC/Watt. If an alternating voltage is applied across a power diode, during the positive half-cycle the diode will conduct the current flow and during the negative half-cycle the diode will not conduct, blocking the flow of current. So the conduction through the power diode occurs only 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 “bridge rectifiers”. Each type of rectifier circuit can be classified as uncontrolled, semi-controlled or fully controlled where an uncontrolled rectifier uses only power diodes, a fully controlled rectifier uses thyristors (SCRs) 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 supply may be single-phase or multi-phase and the simplest of all rectifier circuits is 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. Since 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 in value to an equivalent DC voltage 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, V DC across the load resistor, is calculated as follows. Where Vmax is the maximum or peak voltage value of the sinusoidal AC power supply and VS is the RMS (root mean square) value of the power supply.B. Half-Wave Rectifier with SmoothingCapacitorWhen rectification is used to provide a direct voltage (DC) supply from an alternating (AC) source, the amount of ripple voltage can be further reduced by using higher value capacitors, but there are limitations both in terms in cost and size for the types of leveling 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 connection (C). This configuration causes each diode to conduct in turn when its anode terminal is positive with respect to the center point of the transformer C producing an output during both half cycles, double that of the half-wave rectifier, so it is 100% efficient % as shown below.C . 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) with each diode taking it in turn to supply 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. Since the gap between each half-wave developed by each diode is now filled by the other diode, the average DC output voltage across the load resistor is now double that of the single half-wave rectifier circuit and is approximately 0.637 Vmax of the peak voltage, assuming no losses. Where: VMAX is the maximum peak value in one half of the secondary winding and VRMS is the rms value. The Full Wave Bridge Rectifier Another type of circuit that produces the same output waveform as the full wave rectifier circuit above, is the Full Wave 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 diodesthey conduct 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 Since the current flowing through the load is unidirectional, the voltage developed across the load is also unidirectional as per the previous two-diode full-wave rectifier, so the average DC voltage across the load is 0.637 Vmax. Full Wave Rectifier with Smoothing Capacitor The smoothing capacitor converts the rippled full wave output of the rectifier into a smoother DC output voltage. If we now run the partim 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 this together with the corresponding waveforms. As shown in view B of Figure 4-1, the first section is the TRANSFORMER. The transformer steps up or down the input line voltage and isolates the power 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 pulsating direct current is not desirable. For this reason a FILTER section is used to convert the pulsating DC current into a purer and more desirable form of DC voltage. The final section, the REGULATOR, does just what the name suggests. Maintains power supply output at a constant level despite large variations 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 we need to see how this signal is altered within 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 turns ratio of 1:3. You can calculate the output for 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 VAC (peak-peak) output. Since each diode in the rectifier section conducts 180 degrees of the 360 ​​degree input, the rectifier output will be half, 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; as a result, the signal remains at a more constant dc level. You will see the filtering process more clearly in the discussion of the actual filtering circuits. The output of the filter is a 110 volt DC signal, with AC ripple flowing over the 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, used by the electronic equipment (more commonly called the load). Name other applications of a diode Applications of Diodes Although only two-pin semiconductor devices are available, there are numerous applications of diodes that are vital in modern electronics. Diodes are known to only allow current to move in one direction through the component. This allows a diode to.