An integrated circuit includes a transistor, an UTBOX buried insulating layer disposed under it and a ground plane disposed under the layer. A well is disposed under the plane and a first trench is at the periphery of the transistor and extends through the layer into the well. There is a substrate under the well and a p-n diode on a side of the transistor. The diode comprises first and second zones of opposite doping and the first zone is configured for electrical connection to a first electrode of the transistor. The first and second zones are coplanar with the plane and a second trench for separating the first and second zones. The second trench extends through the layer into the plane to a depth less than an interface between the plane and the well. There is a third zone under the second trench forming a junction between the zones.