Final answer:
To determine the threshold voltage, Vₜₙ, you can use the equation for the drain current in the saturation region of an N-MOSFET. By substituting the given values and solving the resulting equations, you can find Vₜₙ which is approximately 3.3V.
Step-by-step explanation:
To determine the threshold voltage, Vₜₙ, we need to find the gate-to-source voltage at which the N-MOSFET just starts to conduct. In the saturation region, the drain current is given by the equation:
Id = (β/2)((VGs - Vₜₙ)Vds - Vds^2/2)
Where β is the transistor's current gain factor and Vds is the drain-to-source voltage. Rearranging the equation and substituting the given values, we get two equations with two unknowns. By solving these equations, we can find Vₜₙ.
At VGₛ = 4V, Id = 400μA and at VGₛ = 3V, Id = 150μA. By substituting these values in the equation and solving for Vₜₙ, we find that Vₜₙ ≈ 3.3V.