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  • Question

  • Assertion (A): Impatt diode is an avalanche diode.

    Reason (R): Avalanche breakdown phenomenon occurs when a p-n junction is reverse biased.


  • Options
  • A. Both A and R are correct and R is correct explanation of A
  • B. Both A and R are correct but R is not correct explanation of A
  • C. A is correct but R is wrong
  • D. A is wrong but R is correct

  • Correct Answer
  • Both A and R are correct but R is not correct explanation of A 

    Explanation
    An Impatt diode has n+ - p - i - p + structure and is used with reverse bias.

    It exhibits negative resistance and operates on the principle of avalanche breakdown.

    Impatt diode circuits are classified as broadly tunable circuit, low Q circuit and high Q circuit.

    The impedance of Impatt diode is a few ohms. The word Impatt stands for Impact Avalanche Transit Time diode.

    The features of Impatt diode oscillator are : frequency 1 to 300 GHz, Power output (0.5 W to 5 W for single diode circuit and upto 40 W for combination of several diodes), efficiency about 20%.

    Its applications include police radar systems, low power microwave transmitter etc.

    More questions

    • 1. Tesla is a unit of

    • Options
    • A. flux
    • B. field strength
    • C. flux density
    • D. MMF
      • Discuss
    • 2. In a receiver, which of the following device has IF input but RF output?

    • Options
    • A. Demodulator
    • B. Loudspeaker
    • C. Audio amplifier
    • D. Frequency changer
      • Discuss
    • 3. In Fermi-Dirac statistics, the probability of electron occupation of an energy level equal to Fermi level is

    • Options
    • A. 0
    • B. 0.25
    • C. 0.5
    • D. 1
      • Discuss
    • 4. In a shield helix

    • Options
    • A. the spacing between adjacent turns is very large
    • B. the spacing between adjacent turns approaches zero
    • C. the spacing between adjacent turns approaches zero and wire thickness approaches zero
    • D. the spacing between adjacent turns is very large wire thickness approaches zero
      • Discuss
    • 5. Match the following:

      List I List II
      A. 200 MHz 1. SHF
      B. 20 GHz 2. UHF
      C. 500 kHz 3. VHF
      D. 500 MHz 4. MF


    • Options
    • A. A-3, B-1, C-4, D-2
    • B. A-3, B-2, C-4, D-1
    • C. A-3, B-4, C-1, D-2
    • D. A-3, B-4, C-2, D-1
      • Discuss
    • 6. A line of characteristic impedance Z0 branches into two line each with characteristic impedance Z0. The refracted voltage is

    • Options
    • A. zero
    • B. infinite
    • C. equal to incident voltage
    • D. two third of incident voltage
      • Discuss
    • 7. Iron has a body centred cubic structure.

    • Options
    • A. True
    • B. False
      • Discuss
    • 8. A surge voltage

    • Options
    • A. has very high magnitude and very long duration
    • B. has very high magnitude and very small duration
    • C. has very high magnitude and very small duration and can be positive or negative
    • D. can be only positive
      • Discuss
    • 9. The Ohm's law for conduction in metals is

    • Options
    • A. J = ?E
    • B. J =
    • C. J ? ?E
    • D. J ?
      • Discuss
    • 10. The following components are used to measure power output of a 2 kW TWT amplifier

      1. TWT
      2. Low pass/High pass filter
      3. Low power 20 dB attenuator
      4. 40 dB directional coupler with matched load
      5. Power meter.
      The correct sequence of connections of these components is:

    • Options
    • A. 1, 4, 2, 3, 5
    • B. 1, 3, 4, 2, 5
    • C. 1, 2, 4, 3, 5
    • D. 1, 4, 3, 2, 5
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