diodes marketed as "zener diodes" with breakdown above 6V), there can be a very small range of current where hysteresis is possible, and one can build a relaxation oscillator. Depletion region. We came to know about the functions of these diodes. The device is named after Clarence Zener who discovered this electrical property. 407. Avalanche breakdown is not reversible while Zener breakdown is reversible. This high current can cause the breakdown of the diode. What is the Difference Between GSM and CDMA. The temperature coefficient of Avalanche and Zener breakdown is also different. Another difference lies in the nature of doping. A Zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in the figure. Zener Breakdown occurs when the PN-junction diode is highly doped while Avalanche Breakdown occurs only when the PN junction diode is very lightly doped. The efficiency of Avalanche breakdown can be expressed in terms of multiplication factor, M given by Q5: In Zener diode, the breakdown is due to Zener, has a doping. Zener breakdown is caused when there is a high electric field across the junction. 1. NEET Physics Zener Diode Multiple Choice Questions make you feel confident in answering the question in the exam & increases your scores to high. Avalanche breakdown occurs in p-n junction when the Vz is greater than 8 volts. As the magnitude of the reverse bias voltage across the diode increases, the kinetic energy will also increase. Negative resistance characteristic exists; Forward voltage rating is high; Sharp breakdown occurs at a low reverse voltage; All of the above; Answer: (c) Sharp breakdown occurs at a low reverse voltage. Zener diode is a special kind of diode that allows current to flow in the forward direction in the same manner as an ideal diode, but also permit it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage of Zener diode, Zener knee voltage or Zener voltage. This is the Multiple Choice Questions in Special-Purpose Diodes from the book Electronic Devices – Electron Flow Version and Conventional Current Version 8th Edition by Thomas L. Floyd. MCQs on Zener Diode. We also got to know about Zener breakdown and Avalanche breakdown and various terms related to it. A. varactor diode. Zener Diode Multiple Choice Questions Answers; 41. 400 V In Zener diode, the Zener breakdown takes place, 43. The voltage at which the breakdown occurs is called the breakdown voltage. The depletion region is thick. Both P and N are heavily doped. This will cause more and more electrons to collide with one another resulting in the generation of current. Diode using zener breakdown uses heavy doping of the order of 1 impurity atom per 10 5 silicon atoms and is 10 6 volt/cm. This is normally operated in the reverse-region and its application is mostly for voltage reference or regulation. What is the Difference Between Electronic Devices And Integrated Circuit? It occurs in the Zener diodes having Vz between 5 to 8 volts or less than 5V. Both P and N are lightly doped. Electric connection. In Zener diode, the breakdown is due to Zener, has doping, Enter the code above here : The avalanche breakdown is an occurrence of raising the flow of electric current or electrons in insulating material or semiconductor by giving the high voltage. Avalanche Breakdown. A. Avalanche breakdown. When the Vz is greater than 8 volts in a Zener diode, avalanche breakdown occurs because there is an isolation of electrons and holes. 39. A) the potential barrier is reduced to zero. PN junction failure below 5 V is caused primarily by. This feature of avalanche diode provides better surge protection as compared to a Zener diode. In a Zener diode with high breakdown voltage. Answer. 400/√2 V. B. When high reverse voltage is applied to the p-n junction diode, the free electrons (minority carriers) gains large amount of energy and accelerated to greater velocities. Theoretically, Zener breakdown occurs at a lower voltage level then avalanche breakdown in a diode, especially doped for Zener breakdown. If you are looking for a reviewer in Electronics Engineering this will definitely help. Click here to refresh, © 2015 - 2020 MechanicalTutorial.com This Content is copyrighted By MechanicalTutorial.com |All Rights Reserved. The construction of Avalanche diode is similar to the Zener Diode and both Zener and avalanche breakdown is present in these diodes.It is used in avalanche breakdown condition so they have small but significant voltage drop under breakdown condition but the Zener diode always maintain the voltage higher than the breakdown.This feature of diode provide better surge protection than a Zener diode. Unlike Zener diodes, the avalanche diodes maintain a voltage that is higher than the breakdown voltage. This type of junction breakdown is called avalanche breakdown. Difference Between Von Neumann and Harvard Architecture? 1. Difference Between Avalanche & Zener Breakdown One of the major difference between the Avalanche and the Zener breakdown is that the Avalanche breakdown occurs because of the collision of the electrons, whereas the Zener breakdown occurs because of the high electric field.The other differences between them are explained below in the comparison chart. Answer: (C) Sharp breakdown occurs at a low reverse voltage. Answer: (D) 5 mA. MCQs on PN junction diode : 1. B. This contains 10 Multiple Choice Questions for Electrical Engineering (EE) Test: Breakdown Diodes (mcq) to study with solutions a complete question bank. The operating voltage is also different in Zener and Avalanche breakdown. The crucial difference between the Zener and Avalanche breakdown is the operating mechanism. Multiple Choice Questions and Answers on Semiconductor Diode In addition to reading the questions and answers on my site, I would suggest you to check the following, on amazon, as well: Question Bank in Electronics & Communication Engineering by Prem R Chadha D) 4 PN junction. The current in a Zener diode is controlled by, D.Has a constant current passing through it, 45. 40. Avalanche breakdown in a crystal diode occurs when. Avalanche breakdown is defined as the process of applying a high voltage which increases the number of free electrons in the semiconductors and insulating materials. On the other hand, the phenomenon of Avalanche Breakdown occurs because of the collision of electrons that are moving at a very high speed. As far as I know, real avalanche diodes don't have oscillation of this type. In a Zener diode with a high breakdown voltage has (a) Lightly doped P and N (b) P or N is lightly doped (c) Heavily doped P and N (d) None of these. A. B. Zener breakdown. Avalanche breakdown. The Zener and Avalanche breakdown both occur in diode under reverse bias. The avalanche breakdown occurs because of the ionisation of electrons and hole pairs whereas the Zener breakdown occurs because of heavy doping. When the reverse bias voltage starts to increase, the diode intentionally starts an avalanche effect at a … The conventional current in a PN junction diode flows: (a) From positive to negative (b) From negative to positive (c) In the direction opposite to the electron flow. The connection of the Zener is not-destroy whereas the avalanche is destroyed. How is the breakdown region set during the manufacturing of the diode? The associated phenomenon is called Avalanche Breakdown (shown in red color in the figure) and the corresponding voltage is Avalanche Breakdown Voltage (V BR), which is a central phenomenon to the working principle of avalanche diodes. Another special type of diode called the Avalanche diode is used for circuit protection. Contact us: info@mechanicaltutorial.com, Has a constant current passing through it. Here, there is no specific breakdown voltage for the diode, although there is a relationship between the current and the applied voltage in reverse bias. The cut in voltage (or knee voltage) of a silicon diode is (a) 0.2V (b) 0.7V (c) 0.8 V (d) 1.0V Answer-B 3. The Zener breakdown voltage will vary inversely with temperature but the Avalanche breakdown voltage will vary directly with temperature. The Avalanche Breakdown and Zener Breakdown are two different mechanisms by which a PN junction breaks. Avalanche diodes are specially designed for avalanche breakdown and they experience a voltage drop because of the breakdown conditions. The diode using avalanche breakdown uses medium doping and is characterized by breakdown voltage exceeding 6 volts. PN Junction Diode Multiple Choice Questions Answers; 11. C) 3 PN junction. At low carrier density, avalanche breakdown is the dominant mechanism driving high current at high reverse bias voltage. The current through the diode is (A) 10 mA (B) 15 mA (C) 20 mA (D) 5 mA. In a Zener diode with high breakdown voltage, 42. Zener Breakdown has a negative temperature coefficient while Avalanche Breakdown has a positive temperature … Can't read the image? D. None of the above Commonly, Zener diodes are available with breakdown voltage between 1.8 to 200 Volts. The diode may use either zener breakdown or avalanche breakdown. Avalanche and Zener effects. Q6: In a Zener diode. WatElectronics.com | Contact Us | Privacy Policy. Can you mention a few, What is a Ballistic Galvanometer : Construction & Its Working, Arduino Technology Architecture and Its Advantages, Embedded Systems Role in Automobiles with Applications, Traffic Light Control System using Microcontroller, Light Sensor Circuit Diagram with Working Operation, What is 555 Timer IC – Working with Operating Modes, What is RISC and CISC Architecture and their Differences. A semiconductor device especially fabricated to utilize the avalanche or zener breakdown region. d) Both (a) and (c) above Answer-A 2. If the a.c. input to a half-wave rectifier is an r.m.s value of 400/√2 volts, then diode PIV rating is_____? Zener breakdown. B) forward current exceeds a certain value. The depletion region of the Zener is thin whereas the avalanche is thick. These diodes can indefinitely sustain a moderate level of current during breakdown. The avalanche breakdown occurs in both normal diodes and zener diodes at high reverse voltage. A: The Zener diode allows current to flow not only from its anode to its cathode, but then also in the reverse direction when the Zener (breakdown) voltage is reached (Figure 6). Definition. Q7: A Zener diode, having breakdown voltage equal to 15 V, is used in … Avalanche Breakdown. Avalanche diodes (commonly encountered as high voltage Zener diodes) are constructed to break down at a uniform voltage and to avoid current crowding during breakdown. Zener breakdown occurs when the operating voltage is less than 5V while the Avalanche breakdown occurs when the operating voltage is greater than 5V. 7. D) none of the above However, Zener Breakdown occurs due to the breaking of covalent bonds by the strong electric field across the junction. In the case of Avalanche breakdown, the valence band will be pushed in the direction of the conduction band. NEET Physics PN junction diode Multiple Choice Questions make you feel confident in answering the question in the . The main difference lies in the operation of the two diodes. C. Either of … 41. C. shockley diode. There is a hysteresis effect; once avalanche breakdown has occurred, the material will continue to conduct even if the voltage across it drops below the breakdown … In Zener breakdown, the increase in reverse voltage causes the expansion of the depletion layer. C. Either P or N is lightly doped. So, this is all about an overview of Zener breakdown and Avalanche breakdown. A. When forward-biased, the Zener diode behaves like a normal silicon diode with PN junction, allowing a current to pass from the anode to the cathode. B. zener diode. This is also known as avalanche multiplication. Zener Breakdown occurs in heavily doped diodes while Avalanche breakdown takes place in a lightly doped diode. Aha, to answer my own question I see that for some avalanche diodes (i.e. If the applied reverse voltage across the diode is more than Zener voltage, the diode provides a conductive path to the current through it hence, there is no chance of further avalanche breakdown in it. D. Schottky barrier diode Avalanche Breakdown occurs due to the collision of accelerated charge carriers with the adjacent atoms and due to carrier multiplication. Zener diode has… A) 1 PN junction. When PN junction diode is forward bias, forward current is dominated by The diffusion current The displacement current The drift current The drift or diffusion current Answer – (1) 3. This causes the stationary electrons to move towards the conduction band. Zener breakdown occurs when the high electric field is created across the junction. C) reverse bias exceeds a certain value. 8. Another major difference between the Avalanche and Zener breakdown is the movement of the conduction band and valance band. A Varactor Diode performs as A variable resistor A variable capacitor A switching device none of these Answer – (2) 2. The depletion region is thin. Lowest; Moderate; High; Low; Answer:(c) High. The solved questions answers in this Test: Breakdown Diodes quiz give you a good mix of easy questions and tough questions. B) 2 PN junction . On the other hand, Avalanche Breakdown occurs in the device due to the collision of electrons moving at high speed. ) Sharp breakdown occurs due to carrier multiplication is not-destroy whereas the avalanche is destroyed will also increase to towards... 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