In this paper, we propose to derive an analytical model for the doped symmetric double-gate (DG) MOSFET that is valid in all regions of operation. We show that doping the silicon channel can be converted in an equivalent silicon thickness and threshold voltage shift using a formalism developed for the undoped device. Adopting the same physical parameters, we demonstrate that this approach is in agreement with numerical technology computer-aided design simulations. This concept is therefore an interesting basis for a unified model for doped and undoped symmetric DG MOSFETs.