This work investigates the low-frequency noise performance of a long-channel UTBB FD SOI nMOS transistor operated in triode region as typically used for MOSFET-C filter applications. Measurements of the low-frequency noise have been performed over a large temperature range (25–125ºC) at different constant currents above threshold, as a function of the back-gate bias. It is highlighted that in such case, 1/f noise power is dominant, however sufficiently low, in the frequency range of interest for the filters, i.e. below 1 MHz. Noise power strongly reduces with temperature and slightly with positive back-gate bias, which is adequate for the filter tuning.