Optimization of implanted collector doping profiles for a high-speed, low-voltage SiGe HBT process has been investigated experimentally and by device simulations. A low-energy antimony implantation has been combined with a standard selectively implanted collector using phosphorous, to achieve improved control of the collector doping profile. The simulations indicate that the narrow n-type doping peak formed by the antimony implantation allows the cut-off frequency f(T) to be increased without degrading the collector emitter breakdown voltage BVCEO. The fabricated devices demonstrate a highest f(T) of 60 GHz. Depending on the collector profile BVCEO values between 1.5 and 2 V were obtained.