In this paper, we investigate the linearity of undoped body multi-gate independent FinFET (MIGFET) experimentally. The MIGFET device with sub-50 nm body thickness is fabricated on SOI wafers. The device transconductance and its high order derivatives under different bias conditions are measured. RF two-tone inter-modulation distortion measurements are performed. Both the DC and RF measurements demonstrate that the properly biased asymmetric MIGFET provides better linearity performance than that of symmetric MIGFET biased at the conventional moderate inversion linearity "sweet spot". The improved linearity is explained. (c) 2007 Elsevier Ltd. All rights reserved.