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ECE :: Exam Questions Paper

  1. The circuit shown below is the equivalent circuit of which one of the following microwave resonator types?

  2. A.
    Butterfly resonator
    B.
    Parallel-wire resonator
    C.
    Cavity resonator
    D.
    Coaxial line resonator

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  3. Consider the cascade structure of two filters.

    Consider the following statements.

    1. If f1 < f2 then it acts like band-pass filter
    2. If f1 < f2 then it acts like band-pass only if HPF follows LPF in other case it acts like a band stop filter
    3. If f1 > f2 then it acts all stop filter
    The correct statements are:

  4. A.
    1 and 3
    B.
    only 2
    C.
    2 and 3
    D.
    only 3

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  5. A small signal source vi(t) = A cos 20t + B sin106t is applied to a transistor amplifier as shown below. The transistor has β = 150 and hie = 3 kΩ. Which expression best approximates V0(t)

  6. A.
    v0(t) = -1500 (A cos 20t + B sin 106t)
    B.
    v0(t) = -150 (A cos 20t + B sin 106t)
    C.
    v0(t) = -1500 B sin 106t
    D.
    V0(t) = -1500 sin 106t

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  7. Consider the following circuits. Assume all gates to have finite propagation delay

    Which of these circuits generate a periodic square wave at the output Vo?

  8. A.
    (1) only
    B.
    (1) and (2) only
    C.
    (2) (3) and (4) only
    D.
    All (1) (2) (3) and (4)

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  9. Which of the following does not apply to Yagi-Uda antenna

  10. A.
    High gain
    B.
    Reasonably good bandwidth
    C.
    Folded dipole
    D.
    Parasitic elements

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  11. Consider the differential amplifier shown in figure. (Assume β is very high).

    IE(approximately) =

  12. A.
    2 mA
    B.
    1 mA
    C.
    0.5 mA
    D.
    3 mA

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  13. With regard to a transmission line, which of the following statements is correct?

  14. A.
    Any impedance repeats itself every 1/4 on the Smith chart.
    B.
    The S.W.R. = 2 circle and the magnitude of reflection coefficient = 0.5 circle coincide on the Smith chart.
    C.
    At any point on a transmission line, the current reflection coefficient is the reciprocal of the voltage reflection coefficient.
    D.
    Matching eliminates the reflected wave between the source and the matching device location.

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  15. Consider an input x(t) as shown

    System impulse response is:

    If input is passed through this system then output will be zero except

  16. A.
    -2 < t < 6
    B.
    0 < t < 11
    C.
    -2 < t < 5
    D.
    2 < t < 6

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  17. Which of the following quantities cannot be measured/determined using Hall effect?

  18. A.
    Type of semiconductor (p or n)
    B.
    Mobility of charge carriers
    C.
    Diffusion constant
    D.
    Carrier concentration

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  19. Period of the signal is:

  20. A.
    8
    B.
    1
    C.
    24
    D.
    16

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