Device structure for active devices fabricated in a semiconductor-on-insulator (SOI) substrate and design structures for a radiofrequency integrated circuit. The device structure includes a first isolation region in the semiconductor layer that extends from a top surface of a semiconductor layer to a first depth, a second isolation region in the semiconductor layer that extends from the top surface of the semiconductor layer to a second depth greater than the first depth, and a first doped region in the semiconductor layer. The first doped region is disposed vertically between the first isolation region and an insulating layer disposed between the semiconductor layer and a handle wafer of the SOI substrate. The device structure may be included in a design structure embodied in a machine readable medium for designing, manufacturing, or testing an integrated circuit.