Denoting C_G = C₀ WL where C₀ : gate capacitance per unit area,

...................... (2.5)

Saturated region : Under the voltage condition V_GS - V_th = V_DS , a MOS device is said to be in saturation region of operation. In fact, saturation begins when V_DS = V_GS - V_th , since at this point, the resistive voltage drop (IR drop) in the channel equals the effective gate-to-channel voltage at the drain. One may assume that the current remains constant as V_DS increases further. Putting V_DS = V_GS - V_th , the equations (2.2-2.5) under saturation condition need to be modified as

...................................(2.6)

...................................................(2.7)

.....................................(2.8)

.......................................(2.9)