A method of fabricating an integrated circuit includes providing a substrate and creating base-windows in a layer. The method also includes forming a monocrystalline SiGe base layer in each of the base layers, and polycrystalline SiGe elsewhere. Additionally, the method also includes forming a monocrystalline silicon layer over selectively exposed portions of the surface of the substrate. The integrated circuit beneficially includes silicon-based elements such as a lateral pnp transistor, a varactor, and a polysilicon transistor, which are formed on a common substrate with an npn SiGe bipolar transistor.