The charge coupling between the front and back gates is a fundamental property of any fully-depleted silicon-on-insulator (SOI) MOSFET. It is traditionally described by the classical Lim and Fossum model (Lim and Fossum, 1983). However, in the case of lightly-doped ultra-thin-body (UTB) SOI MOSFETs with ultra-thin gate dielectrics, significant deviations from this model have been observed and analyzed over the years. In this paper, we present a thorough review of special features of gate coupling in such devices, combining a large set of results from one-dimensional numerical simulations in classical and quantum-mechanical modes, experimental data and analytical modeling. We show that UTB SOI MOSFETs with ultra-thin gate dielectrics feature stronger modulation of the threshold voltage at the conduction side with opposite gate bias and much wider range of gate voltages for interface coupling than predicted by the Lim and Fossum model. These differences originate from both electrostatic and quantization effects. A simple analytical model taking into account these effects is presented. The model enables an easy assessment of the quantization-induced threshold voltage increase in a long-channel SOI MOSFET versus opposite gate bias and the electric field in the silicon film associated with gate decoupling. (C) 2015 Elsevier Ltd. All rights reserved.