This paper describes modeling and simulation of submicron NMOSFET current drive focusing on carrier velocity-saturation effects. A new simple analytical model is proposed which predicts a significant degradation of drain current in sub- and quarter-micron NMOSFET's. Numerical two-dimensional simulations clarify that the degradation is namely caused by high lateral electric field along the channel, which leads to deep velocity-saturation of channel electrons even at the source end. Experimental data of NMOSFET's, with gate oxide thickness (Tox) of 9-20 nm and effective channel lengths (L(eff)) of 0.35-3.0 mum, show good agreement with the proposed model. It is found that the maximum drain current at the supply voltage of V(dd)=3.3 V is predicted to be proportional to L(eff)0.54 in submicron NMOSFET's, and this is verified with experiments.