The evolution of silicon and silicon-germ anium pnp trans is tors is reviewed in this paper. The motivation for SiGe-pnp trans is tors in Com plem entary Bipolar (CBi) andCBiCMOS is dis cus sed with a view on device param etric param eters that help gage the us efulnes s of thes e devices in analog and RF des ign.We review the bas ic proces s architectures and proces s build ing blocks for CBiCMOS.SiGe-pnp vers us Si-pnp perform ance metrics are highlighted followed by a discus s ion on circuit blocks that benefi t from having near matched com plem entary bipolar trans is tors.