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⚛️ Physics  ·  Semiconductor Electronics  ·  NEET & JEE

The NMOS long-channel drain current in saturation (I<sub>D</sub>,sat) ∝

Answer: (V GS - Vth)².

  • A (V<sub>GS</sub> - Vth)
  • B (V<sub>GS</sub> - Vth)²
  • C (V<sub>GS</sub> - Vth)<sup>0.5</sup>
  • D V<sub>DS</sub>

Correct answer: B. (V<sub>GS</sub> - Vth)²

Explanation: Long-channel MOSFET saturation: I<sub>D</sub> = (1/2) mu C<sub>ox</sub> (W/L) (V<sub>GS</sub> - Vth)². Quadratic dependence on overdrive voltage.

Conductorconduction bandvalence bandbands overlapSemiconductorconduction bandvalence bandsmall gap (~1 eV)Insulatorconduction bandvalence bandlarge gap(> 3 eV)

Conductors have overlapping bands, semiconductors have a small energy gap that can be bridged by heat or doping, and insulators have a large gap that blocks conduction.

Concept context

Band theory, p-n junction, diodes, transistors, logic gates, and integrated circuits.

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