GATE 2014 EC (EC3) – Question 49
MOSFET M₁ shown has W/L = 2, V_DD = 2 V, $\mu_nC_{ox}=100$ µA/V² and V_TH = 0.5 V. Find Vin (V) where M₁ changes from saturation to linear operation.
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Correct answer: 1.4 to 1.6
Explanation
At the boundary Vout=Vin−VT. Let u=Vin−0.5; the saturated current is(1/2)×100µA/V²×2×u²=100µA/V²×u². The10kΩresistor gives Vout=2−u². Set u=2−u², obtaining u²+u−2=0 and physical root u=1V. Thus **Vin=1.5V**.