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

  • Assertion (A): The phenomenon of differential mobility is called transferred electron effect.

    Reason (R): GaAs exhibits transferred electron effect.


  • 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 Gunn diode uses GaAs which has a negative differential mobility, i.e., a decrease in carrier velocity with increase in electric field.

    This effects is called transferred electron effect. The impedance of a Gunn diode is tens of ohms.

    A Gunn diode oscillator has a resonant cavity, an arrangement to couple Gunn diode to cavity, biasing arrangement for Gunn diode and arrangement to couple RF power to load.

    Applications of Gunn diode oscillator include continuous wave radar, pulsed radar and microwave receivers.

    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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