The “Extrinsic” Compact Model of the MOSFET Drain Current Based on a New Interpolation Expression for the Transition Between Linear and Saturation Regimes with a Monotonic Decrease of the Differential Conductance to a Nonzero Value

Previously, we proposed a new interpolation expression to bridge the transition between the linear and the saturation regimes of “intrinsic” MOSFET. This approach, in contrast to the traditional one, gives a monotonic decrease of the differential conductance from the maximum value in the linear regime to the minimum value in the saturation regime. Later, we proposed a linear approximation for an “extrinsic” MOSFET drain current dependence on the “extrinsic” drain bias in the saturation regime for not very high drain bias when nonlinear effects can be neglected. To obtain this approximation, an equation for the output differential resistance of the “extrinsic” MOSFET in saturation regime was obtained, that is similar to the result known from the theory of the common source MOSFET amplifier with source degeneration. In this paper, we combine these two results and present an “extrinsic” compact model for a short-channel MOSFET above threshold drain current with proper account of the differential conductance in the saturation regime.