An integrated circuit includes a high-voltage well having a first doping type, a first doped region and a second doped region embedded in the high-voltage well, the first and second doped regions having a second doping type and spaced apart by a channel in the high-voltage well, source/drain regions formed in the first doped region and in the second doped region, each of the source/drain regions having the second doping type and more heavily doped than the first and second doped regions, first isolation regions spaced apart from each of the source/drain regions, and resistance protection oxide forming a ring surrounding each of the source/drain regions.