A bipolar transistor includes a substrate and a first well in the substrate, the first well having a first dopant type. The bipolar transistor further includes a split collector region in the first well. The split collector region includes a highly doped central region having a second dopant type opposite the first dopant type; and a lightly doped peripheral region having the second dopant type, the lightly doped peripheral region surrounding the highly doped central region. A dopant concentration of the lightly doped peripheral region is less than a dopant concentration of the highly doped central region.