Triode Mode

When V_GS > V_th and V_DS < (V_GS - V_th)

The transistor is turned on, and a channel has been created that allows current to flow in between the drain and the source. The MOSFET operates such as a resistor, controlled by the gate voltage that relative to both the source and drain voltages. The current from drain to source is modeled like:

I_D = μ_n C_ox W/L ((V_GS - V_th) V_DS - V²_DS /2)

In which μ_n is the charge-carrier effective mobility, W is the gate width, L is the gate length and C_ox is the gate oxide capacitance per unit area. The transition from the exponential sub threshold region to the triode region is not as very sharp as the equations suggest.