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ECE :: Exam Questions Paper

  1. The resolution of a DAC depends on which of the following?

  2. A.
    The number of bits
    B.
    Monotonicity
    C.
    Reference voltage
    D.
    The values of resistance

  3. When number of quantization levels are two; then the average transmission power in NRZ polar signaling is __________ that of NRZ unipolar signaling

  4. A.
    1/2
    B.
    1/4
    C.
    1/8
    D.
    none of these

  5. X(t) is a stationary process with the power spectral density Sx(f) > 0 for all f. The process is passed through a system shown below.

    Let Sy, (f) be the power spectral density Y(t). Which one of the following statements is correct?

  6. A.
    Sy(f) > 0 for all f
    B.
    Sy(f) = 0 for |f| > 1kHz
    C.
    Sy(f) = 0 for f = nf0, f0 = 2kHz, n any integer
    D.
    Sy(f) = 0 for f = (2n + 1)f0 = 1 kHz, n any integer

  7. In the following astable multivibrator circuit, which properties of v0(t) depends on R2?

  8. A.
    Only the frequency
    B.
    Only the amplitude
    C.
    Both the amplitude
    D.
    Neither the amplitude nor the frequency

  9. If x(t) = 0 for t < 0 and x(t) contains no impulse or higher order singularities at t = 0. then


  10. The transfer function of a closed loop system is
    where K is the forward path gain. The root locus plot of the system is :


  11. Consider the following statements, regarding an OP AMP:

    1. All types of negative feedback reduce non-linear distortion.
    2. All types of negative feedback reduce the output offset voltage.
    3. Non-inverting (current and voltage) feedback increases the input impedance.
    4. Inverting (current and voltage) feedback decreases input impedance.
    Which of the above statements is/are correct?

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

  13. Which one of the following is applicable to any network-linear or non-linear, active or passive, time-varying or invariant - as long as Kirchhoff laws are not violated?

  14. A.
    Tellegen's theorem
    B.
    Reciprocity theorem
    C.
    Maximum power transfer theorem
    D.
    Superposition theorem

  15. The input and output of a continuous time system are respectively denoted by x(t) and y(t) Which of the following descriptions corresponds to a causal system?

  16. A.
    y(t) = x(t - 2) + x(t + 4)
    B.
    y(t) = x(t - 4) + x(t + 1)
    C.
    y(t) = x(t + 4) + x(t - 1)
    D.
    y(t) = x(t + 5) + x(t + 5)

  17. Which of the following bridges is also used in an oscillator?

  18. A.
    Maxwell
    B.
    Schering
    C.
    Hay
    D.
    Wien