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Semiconductor Devices Flashcards

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  1. A Schottky diode differs from a standard PN junction diode primarily because it:

    Answer: Forms a metal-semiconductor junction with no minority carrier storage, allowing faster switching

    Schottky diodes use a metal-semiconductor junction instead of a PN junction, eliminating minority carrier storage and enabling much faster switching speeds.

  2. What does the term 'transconductance' (gm) describe in a FET?

    Answer: The ratio of the change in drain current to the change in gate-source voltage

    Transconductance (gm = ΔID/ΔVGS) measures how effectively the gate voltage controls the drain current, and is the key gain parameter for FET amplifier design.

  3. A PIN diode is commonly used in RF applications because:

    Answer: Its intrinsic (I) region provides a voltage-controlled resistance at RF frequencies

    The wide intrinsic layer of a PIN diode acts as a variable RF resistance controlled by DC bias current, making it useful for RF switching and attenuation.

  4. When a BJT is in the active (linear) region, which junction biasing condition applies?

    Answer: Base-emitter forward biased; base-collector reverse biased

    Normal active-region operation requires the base-emitter junction forward biased (VBE ≈ 0.7 V for silicon) and the base-collector junction reverse biased.

  5. The maximum reverse voltage a diode can withstand without breakdown is called the:

    Answer: Peak Inverse Voltage (PIV) or Peak Reverse Voltage (PRV)

    The PIV (or PRV) rating specifies the maximum reverse voltage a diode can block; exceeding it causes destructive avalanche or Zener breakdown.

  6. In a JFET, operating the device at VGS = 0 V produces the drain current known as:

    Answer: Maximum drain current IDSS

    IDSS (Drain-Source current with gate Shorted) is the maximum drain current that flows when VGS = 0 V and VDS is in the saturation region.

  7. Avalanche breakdown in a reverse-biased diode occurs due to:

    Answer: High-energy carriers colliding with lattice atoms and creating additional electron-hole pairs (impact ionization)

    Avalanche breakdown results from impact ionization, where accelerated carriers gain enough energy to knock additional electron-hole pairs free, creating a self-sustaining current multiplication.