= 0 for the output transistor, and both transistors are matched.

The drain-to-source voltage can be expressed as V_DS = V_DG + V_GS. With this substitution, the Shichman-Hodges model provides an approximate form for function (V_GS, V_DG):
: where is a technology-related constant associated with the transistor, W/L is the width to length ratio of the transistor, is the gate-source voltage, is the threshold voltage, ? is the channel length modulation