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Zener Diode Presentation


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This Presentation was made for a 2nd year 1st term course.

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Zener Diode Presentation

  1. 1. Presentation on Zener Diode Submitted by: Abidur Rahman 1509056 Electronics and Communication Engineering Pritom Mojumder 1509053 KHULNA UNIVERSITY of ENGINEERING & TECHNOLOGY
  2. 2. A diode is a two-terminal electronic component that conducts primarily in one direction. It blocks current in the opposite direction. This unidirectional behavior is called rectification Introduction 1
  3. 3. A Zener diode is a particular type of diode that allows current to flow not only from its anode to its cathode, but also in the reverse direction, when the so-called "Zener voltage" is reached. Clarence Melvin Zener the American physicist invented Zener diode. Introduction 2
  4. 4. Figure: Zener diode Symbol Introduction Figure: Zener diode Package 3
  5. 5. pn Junction Vo n type carrierconcentration p type x Depletion Layer + + + + + + + + + + + + + +-- -- -- -- -- -- -- E field E field force on electronsE field force on holes How can we make a diode? 4
  6. 6. Construction of Zener Diode The depletion region formed in the diode is very thin, less than 1 µm. Now, even for a small reverse bias voltage of about 5 V, allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material. The Zener diode's operation depends on the heavy doping of its p-n junction. (<1 µm) 5
  7. 7. Important Features • Zener diodes have a highly doped p-n junction. Normal diodes will also break down with a reverse voltage but the voltage and sharpness of the knee are not as well defined as for a Zener diode. • Zener diode can be operated in breakdown region. • In the forward bias direction, the zener diode behaves like an ordinary silicon diode. 6
  8. 8. Graphical Representation 0.7v V IF Reverse Bias Forward Bias VBR 7
  9. 9. Application » In a DC circuit, Zener diode can be used as a voltage regulator to regulate the voltage across small circuits. 8 The function of the regulator is to provide constant output voltage. Zener diode will continue to regulate the voltage until the diodes current falls below the minimum Iz value in the reverse breakdown region.
  10. 10. Application » Zener diode can be used to make a Waveform Clipper. Two Zener diodes facing each other in series will act to clip both halves of an input signal. 9 Waveform clippers can be used to not only reshape a signal, but also to prevent voltage spikes from affecting circuits that are connected to the power supply.
  11. 11. Application » A Zener diode can be applied to a circuit with a resistor to act as a voltage shifter. This circuit lowers the output voltage by a quantity that is equal to the Zener diode's breakdown voltage. 10
  12. 12. Application » Zener diodes are also used in surge protectors to limit transient voltage spikes. 11
  13. 13. Application » Another application of the Zener diode is the use of noise caused by its avalanche breakdown in a random number generator. Figure: Avalanche noise curve 12
  14. 14. • Zener diodes are designed to operate at voltages greater than the breakdown voltage (peak reverse voltage). • Zener diodes are manufactured with a specific breakdown (Zener) voltage. • Zener diodes are packaged the same as P–N junction diodes. • Zener diodes are used to stabilize or regulate voltage. 13
  15. 15. Thank You For Your Attention