Design and On-Wafer Characterization of $G$ -Band SiGe HBT Low-Noise Amplifiers

This paper presents the design and thorough on-wafer characterization of two G-band low-noise amplifiers (LNAs) implemented using 0.13-μm silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) with peak f
_T
/f
_max
of 300/500 GHz. The impact of the substrate network and optimized via interconnections on the SiGe HBT performance is investigated to ensure that maximum performance is extracted from each SiGe HBT. The two LNAs are separately implemented using only cascode pairs and only common-emitter (CE) SiGe HBTs to determine which configuration yields better performance in a multistage G-band LNA. The cascode LNA achieves a peak gain of 24.0 dB at 158 GHz with a mean noise figure (NF) of 8.2 dB from 145 to 165 GHz, while the CE LNA achieves a 17.2 dB of gain at 183 GHz with a mean NF of 8.0 dB across 165-200 GHz. A novel implementation of blackbody noise sources for on-wafer Y-factor NF measurements reduces the waveguide length needed to transition between the antenna and the probe, which significantly reduces the sensitivity to jitter. To the authors' knowledge, these LNAs achieve the lowest reported NF of all SiGe LNAs at these frequencies to date, and the results demonstrate that SiGe HBTs are viable options for millimeter-wave performance-constrained applications.