A device comprises a high voltage n well and a high voltage p well over a buried layer, a first low voltage n well over the high voltage n well, wherein a bottom portion of the first low voltage n well is surrounded by the high voltage n well, an N+ region over the first low voltage n well, a second low voltage n well and a low voltage p well over the high voltage p well, a first P+ region over the second low voltage n well and a second P+ region over the low voltage p well.