Physical electronics devices and ics miscellaneous

Physical electronics devices and ics miscellaneous

Easy Questions

Physical Electronics Devices and ICs

Physical electronics devices and ics miscellaneous
  1. Consider the following statements:
    1. The β of a bipolar transistor reduces if the base width is increased.
    2. The β of a bipolar transistor increases if the doping concentration in the base is increased. Which one of the following is correct?








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    The β of a bipolar transistor reduces if the base width is increased because

    β =
    Ic
    ib
    and base current Ib can be reduces by increasing base width or decreasing doping concentration in the base, resulting increase in β of bipolar transistor. However, the β of a bipolar transistor reduces if the doping concentration in the base region is increased. Therefore statement 1 is TRUE and 2 is FALSE.

    Correct Option: D

    The β of a bipolar transistor reduces if the base width is increased because

    β =
    Ic
    ib
    and base current Ib can be reduces by increasing base width or decreasing doping concentration in the base, resulting increase in β of bipolar transistor. However, the β of a bipolar transistor reduces if the doping concentration in the base region is increased. Therefore statement 1 is TRUE and 2 is FALSE.

  1. The gain of a bipolar transistor drops at high frequencies. This is because of the—








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    The gain of a bipolar transistor drops at high frequencies because of the inter-electrode capacitances. As we know that at high frequency range, the reactance of CC becomes quite small, therefore it behaves like a short circuit. As a result of this, the loading effect of next stage increases, which reduces the voltage gain. In addition to this, the capacitance of the emitter diode plays an important role at high frequencies. It increases the base current of the transistor due to which the current gain (β) reduces. Hence the voltage gain rolls at high frequencies.

    Correct Option: C

    The gain of a bipolar transistor drops at high frequencies because of the inter-electrode capacitances. As we know that at high frequency range, the reactance of CC becomes quite small, therefore it behaves like a short circuit. As a result of this, the loading effect of next stage increases, which reduces the voltage gain. In addition to this, the capacitance of the emitter diode plays an important role at high frequencies. It increases the base current of the transistor due to which the current gain (β) reduces. Hence the voltage gain rolls at high frequencies.

  1. The gain of a bipolar transistor drops at high frequencies. This is because of the—








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    Avalanche multiplication starts when the reverse biased collector-base voltage VCB equals the avalanche breakdown voltage BVCBO. We know that the maximum reverse-biasing voltage which may be applied before breakdown between the collector and base terminals of the transistor, under the condition that the emitter lead be open circuited is represented by the symbol BVCBO. This breakdown voltage is a characteristic of a transistor alone, breakdown may occur because of avalanche multiplication of the current ICO that crosses the collector junction.

    Correct Option: A

    Avalanche multiplication starts when the reverse biased collector-base voltage VCB equals the avalanche breakdown voltage BVCBO. We know that the maximum reverse-biasing voltage which may be applied before breakdown between the collector and base terminals of the transistor, under the condition that the emitter lead be open circuited is represented by the symbol BVCBO. This breakdown voltage is a characteristic of a transistor alone, breakdown may occur because of avalanche multiplication of the current ICO that crosses the collector junction.

  1. Which one of the following statements is correct in respect of BJT?








  1. View Hint View Answer Discuss in Forum

    Avalanche multiplication starts when the reverse biased collector-base voltage VCB equals the avalanche breakdown voltage BVCBO. We know that the maximum reverse-biasing voltage which may be applied before breakdown between the collector and base terminals of the transistor, under the condition that the emitter lead be open circuited is represented by the symbol BVCBO. This breakdown voltage is a characteristic of a transistor alone, breakdown may occur because of avalanche multiplication of the current ICO that crosses the collector junction.

    Correct Option: A

    Avalanche multiplication starts when the reverse biased collector-base voltage VCB equals the avalanche breakdown voltage BVCBO. We know that the maximum reverse-biasing voltage which may be applied before breakdown between the collector and base terminals of the transistor, under the condition that the emitter lead be open circuited is represented by the symbol BVCBO. This breakdown voltage is a characteristic of a transistor alone, breakdown may occur because of avalanche multiplication of the current ICO that crosses the collector junction.

  1. The widths of the base in a GaAs transistor and in a Si transistor (both n-p-n type) are equal. GaAs transistor works at higher frequency—








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    The GaAs transistor works at higher frequency because the base transit time is lower in GaAs.

    Correct Option: C

    The GaAs transistor works at higher frequency because the base transit time is lower in GaAs.