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ECE :: Exam Questions Paper

  1. Which of the following devices has the 'negative resistance' characteristic?

  2. A.
    Reflex klystron
    B.
    Gunn diode
    C.
    P-N-P transistor
    D.
    Magnetron

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  3. Which of the following may result in instability problem?

  4. A.
    Large error
    B.
    High selectivity
    C.
    High gain
    D.
    Noise

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  5. Which of the following are included in the architecture of a computer?

    1. Addressing modes, CPU
    2. Instruction set, data formats
    3. Secondary memory, operating system
    Select the correct answer from the codes given below:

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

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  7. Consider the CMOS circuit shown, where the gate voltage VG of the n-MOSEFT is increased from zero, while the gate voltage of the p-MOSFET is kept constant at 3 V. Assume that, for both transistor, the magnitude of the threshold voltage is 1 V and the product of the transconductor parameter and the (W/L) ratio, i.e. the quality μC0x(W/L), is 1mA. V-2.

    For small increase in VG beyond IV, which of the following gives the correct description of the region of operation of each MOSFET?

  8. A.
    Both the MOSFET are in saturation region
    B.
    Both the MOSFET are in triode region
    C.
    n-MOSFET is in triode and p-MOSFET is in saturation region
    D.
    n-MOSFET is in saturation and p-MOSFET is in triode region

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  9. Two identical NMOS transistors M1 and M2 are connected as shown below. Vbias is chosen so that both transistors are in saturation. The equivalent gm of the pair is defined to be
    at constant Vout
    The equivalent gm of the pair is

  10. A.
    the sum of individual gm's of the transistors
    B.
    the product of individual gm's of the transistors
    C.
    nearly equal to the gm of M1
    D.
    nearly equal to gm / g0 of M2

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  11. In a digital voltmeter the oscillator frequency is 400 kHz and the ramp voltage falls from 8 V to 0 V in 20 ms. What is the number of pulses counted by the counter?

  12. A.
    800
    B.
    2000
    C.
    4000
    D.
    8000

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  13. The silicon sample with unit cross-sectional area shown below is in thermal equilibrium. The following information is given: T = 300 K, electronic charge = 1.6 x 10-19C, thermal voltage = 26mV and electron mobility = 1350 cm2/V-s

    The magnitude of the electron drift current density at x = 0.5 μm is

  14. A.
    2.16 x 104 A/cm2
    B.
    1.08 x 104 A/cm2
    C.
    4.32 x 103 A/cm2
    D.
    6.48 x 102 A/cm2

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  15. Which of the following antennas uses a number of varying length parallel elements?

  16. A.
    Helical antenna
    B.
    Pyramidal Horn
    C.
    Comer reflection antenna
    D.
    Yagi-Uda antenna

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  17. For a second order instrument, the optimum range of ξ (damping ratio), which gives good frequency response over a wide range of frequencies is

  18. A.
    0.5 to 0.6
    B.
    0.6 to 0.7
    C.
    0.7 to 0.8
    D.
    0.8 to 1.0

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  19. If the connection of two-port is such that the transmission matrix of the overall network is the product of the transmission matrices of the individual networks, what type of connection is it?

  20. A.
    Series connection
    B.
    Cascade connection
    C.
    Parallel connection
    D.
    None of the above

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