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ECE :: Electronic Devices and Circuits

  1. The number of doped regions in a bipolar junction transistor is

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

  3. Donor energy level is n type semiconductor is very near valence band.

  4. A.
    True
    B.
    False

  5. GaAs has an energy gap 1.43 eV the optical cut off wavelength of GaAs would lie in the

  6. A.
    visible region of the spectrum
    B.
    infrared region of the spectrum
    C.
    ultraviolet region of the spectrum
    D.
    for ultraviolet region of the spectrum

  7. Which of the following is basically a voltage controlled capacitance?

  8. A.
    Zener diode
    B.
    Diode
    C.
    Varactor diode
    D.
    LED

  9. When the i-v curve of a photodiode passes through origin the illumination is

  10. A.
    maximum
    B.
    minimum
    C.
    zero
    D.
    equal to rated value

  11. An n type silicon bar 0.1 cm long and 100 μm2 in cross-sectional area has a majority carrier concentration of 5 x 1020/m3 and the carrier mobility is 0.13 m0/V-s at 300k. If the charge of an electron is 1.6 x 10-19 coulomb, then the resistance of the bar is

  12. A.
    106 ohm
    B.
    104 ohm
    C.
    10-1 ohm
    D.
    10-4 ohm

  13. The threshold voltage of a MOSFET can be lowered by

    1. using thin gate oxide
    2. reducing the substrate concentration
    3. increasing the substrate concentration.
    Of the above statement

  14. A.
    3 alone is correct
    B.
    1 and 2 are correct
    C.
    1 and 3 are correct
    D.
    2 alone is correct

  15. In which device does the extent of light controls the conduction

  16. A.
    photovoltaic cell
    B.
    photo electric relay
    C.
    LED
    D.
    photo sensitive device