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Semiconductor Devices & Circuits Flashcards

7 cards from real CET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. In a transistor amplifier, the quiescent point (Q-point) represents:

    Answer: The DC operating point with no AC signal applied

    The Q-point defines the DC bias conditions (VCE, IC) at which the transistor operates before any AC signal is applied.

  2. What is the primary advantage of a Darlington pair transistor configuration?

    Answer: Very high current gain (β1 × β2)

    A Darlington pair cascades two BJTs so the combined current gain is approximately the product of both individual gains.

  3. Which parameter defines the maximum safe operating temperature junction for a semiconductor device?

    Answer: TJ(max)

    TJ(max) specifies the maximum allowable junction temperature, beyond which the device may suffer permanent damage or failure.

  4. In a class-A amplifier, the transistor conducts for:

    Answer: 360° of the input cycle

    Class-A amplifiers bias the transistor to conduct for the entire 360° of the input waveform, providing low distortion but low efficiency.

  5. The Early effect in a BJT refers to:

    Answer: Modulation of the effective base width by collector voltage

    The Early effect (base-width modulation) describes how increasing VCE narrows the base width, slightly increasing collector current.

  6. A photodiode is typically operated in which bias condition for fastest response?

    Answer: Reverse bias (photoconductive mode)

    Reverse-biased (photoconductive) mode widens the depletion region and reduces junction capacitance, giving the fastest response time.

  7. What is the key difference between a depletion-mode and an enhancement-mode MOSFET?

    Answer: Depletion-mode devices have a built-in channel at VGS = 0; enhancement-mode devices do not

    Depletion-mode MOSFETs are fabricated with a pre-existing channel, so they conduct at VGS = 0; enhancement-mode devices require an applied VGS to form the channel.