General large-signal charge-control equations for the MOSFET drain and source current under nonquasistatic conditions

General large-signal charge-control equations for the drain and source terminal currents of the long-channel MOSFET on a previously proposed recursion relation are presented. These equations are physically derived following Van Nielen´s iterative procedure to reveal the relaxation mechanism in the MOSFET channel under nonquasistatic conditions. The relation between the channel charge partitioning model and the general theoretical development is discussed. This makes it possible to put various solution techniques reported for the MOSFET nonquasistatic problem into perspective. Within the theoretical framework of this work, it is observed that, in general, the drain and source currents share a common relaxation time. The general charge-control equations presented in the paper differ from the simple first-order nonquasistatic current equations, in that they incorporate correction terms to account for the otherwise neglected high-order nonquasistatic effects. Quasistatic formulation of these correction terms is used to illustrate their effects on transient response. It is shown that consistency in the introduction of such correction terms to specific models is crucial to the continuity in current values throughout the transient