An analytic saturation model for drain and substrate currents of conventional and LDD MOSFETs

An analytic saturation model for conventional and lightly doped drain (LDD) MOSFETs is developed by using the pseudo-two-dimensional approximation in the channel and drain regions to obtain both the channel length modulation factor and the maximum electric field. Using the established I-V model in the linear region, the drain currents of conventional and LDD MOSFETs can be explicitly calculated. The substrate currents of conventional/LDD MOSFETs are calculated by using an existing simplified substrate current formula and the maximum electric field model. It is shown that the accuracy of the maximum electric field is acceptable for calculating the substrate currents of conventional/LDD MOSFETs. The parameters used in the model can be determined by the existing extraction methods and the optimization technique. The saturation model is shown to be valid for a wide range of channel lengths and bias conditions