Variability of low frequency noise in moderately-sized MOSFETs — A model for the area- and gate voltage-dependence

In this paper, a thorough statistical investigation of low frequency noise (LFN) variability in MOSFETs is presented. In smaller-sized devices, noise fluctuations are area-dominated. In moderate- to large-sized transistors (Area ≫ 1μm²), normalized noise fluctuations are roughly independent of area, but show a distinct degradation towards weak inversion (subthreshold). A new model is proposed for the gate-voltage dependence of 1/f noise variations in moderately-sized transistors. We show that the gate-voltage dependence may be related to transconductance-to-current ratio g_m/I_D. Extensive measurements of low frequency noise variability in experimental 180nm CMOS confirm the newly proposed model.