Physical noise modeling of SOI MOSFETs with analysis of the Lorentzian component in the low-frequency noise spectrum

The implementation of a general physics-based compact model for noise in silicon-on-insulator (SOI) MOSFETs is described. Good agreement is shown between model-predicted and measured low-frequency (LF) noise spectra. In particular, the behavior of an excess Lorentzian component that dominates the LF noise spectra of SOI MOSFETs is investigated. Shot noise associated with the generation and removal (via recombination or a body contact) of body charge is shown to underlie the behavior of the Lorentzian in both floating-body and body-tied-to-source SOI MOSFET's operating under partially depleted or "mildly" fully depleted conditions; the Lorentzian is suppressed when the body is "strongly" fully depleted. Good physical insight distinguishes the behavior of the Lorentzian components in all these devices, and predicts the occurrence of additional excess noise sources in future scaled technologies. Simple analytic expressions that approximate the full model are derived to provide the insight.