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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.

    Microwave Communication problems

    Search Results

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    • Options
    • A. converts velocity modulation into current modulation of beam
    • B. converts current modulation into velocity modulation of beam
    • C. both (c) and (b)
    • D. neither (a) nor (b)
      • Discuss
    • 2. The radiation resistance of a circular loop of one turn is 0.01 ohm. For 5 turn loop the radiation resistance is

    • Options
    • A. 0.002 ?
    • B. 0.01 ?
    • C. 0.05 ?
    • D. 0.25 ?
      • Discuss
    • 3. The electric field in a TWT due to applied signal

    • Options
    • A. is directed along the helix axis
    • B. is directed radially from helix axis
    • C. is inclined to the helix axis by about 60°
    • D. is inclined to the helix axis by about 45°
      • Discuss
    • 4. Varactor diodes use

    • Options
    • A. silicon
    • B. GaAs
    • C. either (a) or (b)
    • D. neither (a) nor (b)
      • Discuss
    • 5. If load impedance ZL >> Z0, then

    • Options
    • A. Z0 = ZL (VSWR)
    • B. ZL = Z0 (VSWR)
    • C. ZL = Z0 (VSWR - 1)
    • D. ZL = Z0 VSWR
      • Discuss
    • 6. A TE10 rectangular waveguide is to be designed for operation over 25-35 GHz and the band centre is 1.5 times the cutoff frequency. The dimension of broadside is

    • Options
    • A. 15 mm
    • B. 10 mm
    • C. 9 mm
    • D. 7.5 mm
      • Discuss
    • 7. In the given figure a short circuited transmission line resonator If n = 1, 2, 3...

    • Options
    • A. For series reasonance ?l = np and for parallel resonance
    • B. For series resonance and for parallel resonance ?l = np
    • C. ?l = np for both series and parallel resonance
    • D. for both series and parallel resonance
      • Discuss
    • 8. The duty cycle of a radar transmitter is equal to

    • Options
    • A. (PRF) (pulse width)
    • B. (PRF)/(pulse width)
    • C. (pulse width)/(PRF)
    • D. (pulse width) + (PRF)
      • Discuss
    • 9. Out of modes TE20 and TE30 of propagation of electromagnetic engery

    • Options
    • A. both have the same cutoff frequency
    • B. TE20 has lower cut off frequency as compared to TE30
    • C. TE30 has lower cutoff frequency as compared to TE20
    • D. either (a) or (c)
      • Discuss
    • 10. In the given figure forward voltage wave has a magnitude

    • Options
    • A. 90 V
    • B. 60 V
    • C. 30 V
    • D. 10 V
      • Discuss

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