A radio frequency (RF) LDMOSFET with step drift doping profile on a conventional thin film SOI substrate used for mainstream VLSI technology is evaluated. Detailed simulation indicates that step drift doping can enable increase in the breakdown voltage by as much as 21% in comparison to the conventional uniformly doped drift (UD) LDMOS. In the on-state the kink present in the I-V characteristic of the UD device is eliminated. The other improvements over the UD counterpart include improved on-state breakdown performance, reduced parasitic feedback capacitance, lower on-resistance, improved drain current saturation behaviour and reduced self-heating at bias point. (C) 2003 Elsevier Ltd. All rights reserved.