With today's technology downscaling, the coupling through the substrate becomes an important limiting factor for the performance of mixed-mode high-frequency integrated circuits, filters, convertors, transmission lines and even single MOSFETs. This paper presents original studies on the coupling through the substrate in SOI devices and on substrate engineering which allows to suppress this effect. Particular attention is paid to the Silicon-on-Nothing (SON) MOSFET architecture as one of the most promising solutions to suppress the effect of parasitic coupling through the substrate on the transistor behavior. (C) 2008 Elsevier B. V. All rights reserved.