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Home ‣ Electronics and Communication Engineering ‣ Microwave Communication See What Others Are Saying!
  • Question

  • Assertion (A): PIN diode is commonly used for microwave control.

    Reason (R): A PIN diode uses heavily doped p and n materials.


  • 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
    A PIN diode has an intrinsic (i) layer between p and n layers. When reverse bias is applied depletion layers are formed at p-i and i-n junctions.

    The effective/width of depletion layer increases by the width of i layer. It can be used as a voltage controlled attenuator.

    At high frequencies the rectification effect ceases and impedance of diode is effectively that of i layer.

    This impedance varies with the applied bias. It is used in high frequency switching circuits, limiters, modulators etc.

    More questions

    • 1. The power requirements of a DRAM in active and stand by modes is about

    • Options
    • A. 350 mW and 5 mW respectively
    • B. 350 mW each
    • C. 5 mW each
    • D. 350 mW and 100 mW respectively
      • Discuss
    • 2. The different access methods which permit many satellite users to operate in parallel through a single transponder without interfering with each other as

    • Options
    • A. Frequency Division Multiple Access (FDMA)
    • B. Time Division Multiple Access (TDMA)
    • C. Code Division Multiple Access (CDMA)
    • D. All of the above
      • Discuss
    • 3. Match the following:

      List I List II
      A. T (Reflection coefficient) = 0 1. (ZL - Zo)/(ZL + Zo)
      B. T = - 1 2. ZL = Zo
      C. T = + 1 3. ZL = 0
      D. - 1 < T < + 1 4. ZL = ?


    • Options
    • A. A-2, B-3, C-4, D-1
    • B. A-2, B-4, C-1, D-3
    • C. A-1, B-2, C-3, D-4
    • D. A-3, B-2, C-4, D-1
      • Discuss
    • 4. Assertion (A): Ferromagnetic materials possess ferromagnetic properties only when temperature is less than paramagnetic curie temperature.

      Reason (R): For a ferromagnetic material for T > ?f.


    • Options
    • A. Both A and R are true and R is correct explanation of A
    • B. Both A and R are true but R is not correct explanation of A
    • C. A is true but R is false
    • D. A is false but R is true
      • Discuss
    • 5. Bode magnitude plot is drawn between

    • Options
    • A. magnitude of network function and ?
    • B. dB magnitude and log ?
    • C. dB magnitude and ?
    • D. loge (magnitude) and log ?
      • Discuss
    • 6. A two branch parallel circuit has a 20 ? resistance and 1 H inductance in one branch and a 100 ?F capacitor in the second branch. It is fed from 100 V ac supply, at resonance, the input impedance of the circuit is

    • Options
    • A. 500 ?
    • B. 50 ?
    • C. 20 ?
    • D. 5 ?
      • Discuss
    • 7. The temperature coefficient of a thermistor

    • Options
    • A. is positive
    • B. is negative
    • C. zero
    • D. may be positive or negative depending on its composition
      • Discuss
    • 8. An amplifier has a large ac input signal. The clipping occurs on both the peaks. The output voltage will be nearly a

    • Options
    • A. sine wave
    • B. square wave
    • C. triangular wave
    • D. (a) or (c)
      • Discuss
    • 9. In the figure shown, A1, A2, A3 are identical Ammeters. If A1 and A3 read 5 and 13 A respectively, reading of A2 will be

    • Options
    • A. 8
    • B. 13 A
    • C. 18
    • D. 12 A
      • Discuss
    • 10. A relaxation oscillator uses

    • Options
    • A. tunnel diode
    • B. UJT
    • C. both tunnel diode and UJT
    • D. PIN diode
      • Discuss

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