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⚛️ Physics  ·  Semiconductor Electronics  ·  NEET & JEE

Channel length modulation in MOSFET causes:

Answer: Non-zero output conductance (dI_D/dV_DS) in saturation.

  • A A shift in the threshold voltage of the transistor itself
  • B Non-zero output conductance (dI_D/dV_DS) in saturation
  • C Complete pinch-off of the channel with zero drain current
  • D Leakage current flowing directly through the gate oxide

Correct answer: B. Non-zero output conductance (dI_D/dV_DS) in saturation

Explanation: Channel length modulation (lambda parameter): effective channel shortens as V<sub>DS</sub> increases. I<sub>D</sub>,sat = (1/2)mu C<sub>ox</sub>(W/L)(V<sub>GS</sub>-Vth)²(1+lambda V<sub>DS</sub>). Finite output resistance.

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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