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ECE :: Exam Questions Paper

  1. Consider the following statements:

    1. With increase in temperature Fermi-level tries to come in between the energy gap exactly at middle
    2. Mobility of electron in GaAs is very high compared to mobility of hole
    3. In LED, the light energy radiated due to recombination with the aid of traps.
    Which of these statements are true?

  2. A.
    1 and 2
    B.
    1, 2 and 3
    C.
    2 and 3
    D.
    1 and 3

  3. For good quality signal transmission all frequency components should have the same transmission delay, td and same phase shift-Φs. What can be said about the statement?

  4. A.
    Correct
    B.
    True from td but not for Φs
    C.
    Not true for td but true for Φs
    D.
    Both td and Φs are not involved in quality

  5. The following series RLC circuit with zero initial conditions is excited by a unit impulse function δ(t)

    For t > 0, the voltage across the resistor is


  6. In a CMOS CS amplifier, the active load is obtained by connecting a

  7. A.
    p channel current mirror circuit
    B.
    n channel transistor
    C.
    p channel transistor
    D.
    BJT current mirror

  8. An audio signal is band limited to 4 kHz. It is sampled at 8 kHz. What will be the spectrum of the sampled signal?

  9. A.
    -4 kHz to 4 kHz
    B.
    -8 kHz to 8 kHz
    C.
    every 4n kHz repeating
    D.
    every ± 8 kHz and operating as well as at zero (k integer)

  10. Consider the equation s2 + 2s + 2 + K(s + 2) = 0. Where do the roots of this equation break on the root loci plot?

  11. A.
    -3.414
    B.
    -2.414
    C.
    -1.414
    D.
    -0.414

  12. The characteristic equation of a closed loop system is (s + 2) (s + 3) + K = 0. The centroid of the asymptotes in root locus is:

  13. A.
    2.5
    B.
    -2.5
    C.
    0.5
    D.
    -0.5

  14. Value of 'K' for the system for which the system is stable:

  15. A.
    K < 1
    B.
    K > 1
    C.
    K < 2
    D.
    K > 2

  16. The number of roots of s3 + 2s2 + 7s + 3 = 0 in the left half of the s-plane is :

  17. A.
    zero
    B.
    one
    C.
    two
    D.
    three

  18. Consider a feedback control system with open loop transfer function The type of the closed loop system is __________ .

  19. A.
    zero
    B.
    one
    C.
    two
    D.
    three