Analog electronics circuits miscellaneous


Analog electronics circuits miscellaneous

Analog Electronic Circuits

  1. If the transistor parameter are β = 180 and early voltage VA = 140 V and it is biased at ICQ = 2 mA, the values of hybrid-π parameter gm, rx and r0 are respectively:









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    gm =
    IC Q
    =
    2 × 10–3
    = 0.0769 ≈ 77 mA/V
    VT26 × 10–3

    rπ =
    β
    =
    180
    = 2.33 kΩ
    gm77 × 10–3

    r0 =
    | VA |
    =
    140
    = 70 kΩ
    ICQ2 × 10–3

    Correct Option: C

    gm =
    IC Q
    =
    2 × 10–3
    = 0.0769 ≈ 77 mA/V
    VT26 × 10–3

    rπ =
    β
    =
    180
    = 2.33 kΩ
    gm77 × 10–3

    r0 =
    | VA |
    =
    140
    = 70 kΩ
    ICQ2 × 10–3


  1. The bandwidth of an RF tuned amplier is dependent on:









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    Bandwidth =
    f0
    Q

    where, f0 = resonant frequency & Q = quality factor

    Correct Option: A

    Bandwidth =
    f0
    Q

    where, f0 = resonant frequency & Q = quality factor



  1. Match each of the items A, B and C with and appropriate item from 1, 2, 3, 4 and 5.
    (A) Common-collector amplifier.
    (B) Common-emitter amplifier.
    (C) Common-base amplifier.
    1. provides voltage gain but no current gain
    2. provides current gain but no voltage gain
    3. provides neither voltage nor power gain
    4. provides neither current nor power gain
    5. provides both voltage and current gain









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    A – 2
    B – 5
    C – 1

    Correct Option: D

    A – 2
    B – 5
    C – 1


  1. Match each of the items A, B and C with and appropriate item from 1, 2, 3, 4 and 5. In an extrinsic semiconductor:
    (A) the resistivity decreases
    (B) the temperature coefficient of resistivity is negative.
    (C) the photo conductivity is low
    1. the doping concentration is low
    2. the length of the semiconductor is reduced
    3. the band gap is high
    4. the area of cross-section of the semiconductor is increased
    5. the doping concentration is increased









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    A – 5
    B – 5
    C – 1

    Correct Option: B

    A – 5
    B – 5
    C – 1



  1. Match each of the items A, B and C with and appropriate item from 1, 2, 3, 4 and 5.
    In a JFET
    (A) the pinch-off voltage decreases
    (B) the transconductance increases
    (C) the transit time of the carriers in the channel is reduced
    1. the channel doping is reduced
    2. the channel length is increased
    3. the conductivity of the channel increased
    4. the channel length is reduced
    5. the gate area is reduced









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    We know that, pinch-off voltage

    | VP | =
    q·ND·a2
    where VP = pinch-off voltage
    2∈0

    a = channel width
    ND = doping concentration
    ∈ = relative permeability Hence
    A – 1
    ID = b ND. µn
    W
    . VDS → hence B – 4
    L

    Gate decide the flow of electrons to the drain. Hence C – 5.
    Therefore
    A – 1
    B – 4
    C – 5
    Hence alternative (A) is the correct choice.

    Correct Option: A

    We know that, pinch-off voltage

    | VP | =
    q·ND·a2
    where VP = pinch-off voltage
    2∈0

    a = channel width
    ND = doping concentration
    ∈ = relative permeability Hence
    A – 1
    ID = b ND. µn
    W
    . VDS → hence B – 4
    L

    Gate decide the flow of electrons to the drain. Hence C – 5.
    Therefore
    A – 1
    B – 4
    C – 5
    Hence alternative (A) is the correct choice.