Ultrahigh-performance 8-GHz SiGe power HBT

This letter has demonstrated the state-of-the-art SiGe power heterojunction bipolar transistors (HBTs) operating at 8 GHz. In a common-base configuration, a continuous wave output power of 27.72 dBm with a concurrent power gain of 12.19 dB was measured at a peak power-added efficiency of 60.6% from a single SiGe HBT with a 3-μm emitter finger stripe width and a 1340 μm² total emitter area. The highest power-performance figure of merit (FOM) of 3.8×10⁵ mW/spl middot/GHz² achieved from the device was resulted from using an optimized SiGe heterostructure and a compact device layout, which is made possible with a heavily doped base region.