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JEE Main · 2021 · 27 Aug 2021 · Shift 1 · Semiconductors

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For a transistor in CE mode to be used as an amplifier, it must be operated in :
  1. (A)Saturation region only
  2. (B)Both cut-off and Saturation
  3. (C)The active region only✓ Correct
  4. (D)Cut-off region only

Answer: (C)

Solution

In the common-emitter configuration the transistor amplifies linearly only when the emitter–base junction is forward biased and the collector–base junction is reverse biased, which defines the active region. In saturation both junctions are forward biased and the device behaves as a closed switch, while in cut-off both are reverse biased and it behaves as an open switch; neither allows amplification. The transistor must be operated in the active region only.

JEE Main · 2021 · 27 Aug 2021 · Shift 1 · Single correct option

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