For the first time, the high frequency (HF) performance of an ultra-thinned body (UTB) fully depleted silicon-on-insulator (FDSOI) incorporating TiN/HfO2 gate stack is reported. Full small signal equivalent parameters of UTB-FDSOI are extracted and analysed in detailed. It is revealed that UTB-FDSOI with longer unit width W-U (same total width W-TOT) results in slightly higher g(m) that leads to better HF performance. Despite of the mobility degradation due to the quality of the interface between the high-K dielectric and silicon, the measured transition frequency (f(T)) still corresponds well to that predicted from the ITRS roadmap. Optimising the gate stack for low R-G is crucial as huge RG in the current technology is the key parameter responsible for the low f(MAX) obtained. This work can also be considered as the first ever experimental device measured suitable to be used for the Low STand-by Power (LSTP)-based RF/mobile application. (C) 2009 Elsevier Ltd. All rights reserved.