RF MOS varactor

An integrated circuit includes a substrate having a first conductivity type. A well formed at an upper surface has a second, opposite conductivity type and a first dopant concentration. First and second STI structures are formed and a polysilicon gate structure is formed between the first and second STI structures. The polysilicon gate structure extends over a first side of the first STI structure and over a first side of the second STI structure. A first doped region is formed within the well at the upper surface and on a second side of the first STI structure and a second doped region is formed within the well at the upper surface and on a second side of the second STI structure. The first and second doped regions each have the second conductivity type and a second dopant concentration that is greater than the first dopant concentration.