A Collector-Up SiGe-HBT for High Frequency Applications

Short Abstract— A new method for realization of a collector-up SiGe-HBT on SOI substrate for high frequency applications is introduced and its dc and ac characteristics are predicted using a two dimensional device simulator. The simulation results show considerable improvements in all aspects of dc current gain, fT, fmax, and maximum available gain/maximum stable gain (MSG/MAG) in comparison with a state of the art emitter-up SiGe-HBT with similar doping profile and germanium content. Another advantage of common-emitter collector-up transistor is that the emitter is connected to the ground and the substrate capacitor is shorted. This provides a higher frequency performance for circuit designs.