...................... (2.11)

The current expression pertains to a MOSFET with effective channel length L_eff, operating in saturation. The above equation depicts the condition known as channel length modulation , where the channel is reduced in length. As the effective length decreases with increasing V_DS , the saturation current I_DS(SAT) will consequently increase with increasing V_DS . The current given by (2.11) can be re-written as

.......................... (2.12)

The second term on the right hand side of (2.12) accounts for the channel modulation effect. It can be shown that the factor channel length is expressible as

One can even use the empirical relation between and V_DS given as follows.