This paper presents low frequency noise investigations in ultrathin oxide MOSFETs of advanced bulk CMOS technology. Simple analytical models for the drain and gate-leakage current noise are presented and analyzed with respect to noise measurements. The developed formulations of the different 1/f noise sources are based on a flat band voltage concept and proves very effective in describing the overall drain current noise as well as the gate current one. In particular, the huge excess drain noise experimentally observed in large area devices is explained by sum of both drain and gate current noise contributions using gate-partitioning coefficients. (c) 2005 Elsevier Ltd. All rights reserved.