SiGe:C profile optimization for low noise performance

Today's state-of-the-art SiGe BiCMOS processes show impressive high-frequency performance, with ƒ T and ƒ MAX exceeding 500GHz. However, SiGe can also offer significant performance gain at more moderate application frequencies. In this paper we discuss the optimization of SiGe heterojunction bipolar transistors (HBTs) for very low noise applications in the 2–10GHz range. By careful tuning of the base-profile, minimum noise figures below 0.55dB and 0.35dB are obtained at 10GHz and 2GHz respectively.