The influence of different physical mechanisms on MOSFET linearity is analyzed using 2D TCAD device simulations. In particular, the RF linearity performance of 50 nm gate length SOI and DG-MOSFETs are investigated and compared with traditional bulk MOSFETs. We employ the hydrodynamic (HD) transport model to account for nonequilibrium carrier dynamics and the density gradient approximation for quantum mechanical effects. Impact ionization of channel carriers and self-heating effect (SHE) are also accounted for in the thin-body devices. Our results disclose the relationship between various aspects of device physics and linearity. We show that linearity performance is particularly sensitive to non-local effects and are lowered due to SHE. Quantum mechanical effects appear to have a small positive impact on linearity. Drift-diffusion approximation is found to be unreliable for linearity analysis of DG MOSFETs due to large overestimation from this model. We also observe that linearity has an anomalous monotonous dependence on the ambient temperature. (C) 2004 Elsevier Ltd. All rights reserved.