An analytical model for the anomalous behavior of the halo or pocket implanted MOSFETs is presented for both strong and weak inversion operation. Even though most of the drain current reduction due to the pocket implantation can be explained by the effective threshold voltage of halo MOSFETs, a further decrease has been observed that can be attributed to the effects of the halo implants on the effective mobility as well as threshold voltage of these devices. Taking into account the effect of the regionally distinctive distributions of the physical quantities related to the charge transport, a simple drain current model suitable for implementation in circuit simulators is developed. The presented analytical model is shown to agree well with 2D simulations and experiments. The reduced dependency of the subthreshold current on the gate length is also explained. (C) 2002 Elsevier Science Ltd. All rights reserved.