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This paper presents a model for estimating the drain current in deep submicron (DSM) CMOS devices based on Sakurai and Newton's (1991) work, and hence is referred to as the modified SN-model. The proposed model preserves the simplicity of the SN-model while providing accurate drain current estimates for varying device widths. Manually computed current and delay values for inverter circuits via the proposed model match SPICE level 49 within 1.2% average (3% maximum) error in 0.25 μm and 0.18 μm CMOS processes over a wide range of transistor widths, fanouts, and input rise/fall times. A generalized delay model for circuits with interconnect is also proposed with accuracy within 3% error over a wide range of buffer sizes and interconnect lengths. The proposed model has been successfully incorporated into a senior level circuit design course at the University of Illinois at Urbana-Champaign.