Direction: Consider the common source amplifier shown below. The transistor parameter are VTN = 1.5 V, Kn = 0.5 mA/ V2, and λ = 0.01 V– 1. The resistance of source is RS = 4 kΩ.
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The amplifier output resistance is:
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- 20.6 kΩ
- 70.9 kΩ
- 29.1 kΩ
- 104 kΩ
Correct Option: A
From small-signal equivalent circuit shown in fig.
Ri = R1 || R2 = 70.9 || 29.1 = 20.6 kΩ
