The DC and transient operations of asymmetrically doped CMOS inverters are investigated. The asymmetrical doping consists of a halo around either the source or the drain. We investigate the DC and transient characteristics of devices and CMOS inverters that contain these halos. To facilitate the investigation, a new algorithm for mixed mode device/circuit simulation is developed. We find that the utilization of the source halo provides significant improvement in the DC and switching characteristics of both devices and CMOS inverters. The drain halo improves performance but gives rise to increased source-drain leakage currents. The effects of narrowing the halo doping is also investigated. (C) 2002 Published by Elsevier Science Ltd.