Broadband Noise Characterization of SiGe HBTs Down to 4K

In this study, we present an extensive analysis of noise characteristics in Si/SiGe:C Heterojunction Bipolar Transistors (HBTs) within a 0.13 ┬Ám BiCMOS technology, spanning a wide temperature range from 293 to 4 K and a frequency spectrum from 10 kHz to 12 GHz. This investigation is unprecedented in its coverage of such temperature and frequency intervals. We notice an augmentation in the flicker noise coefficient $K_{F}$, increasing by a factor of 5.5 at 4 K. Additionally, the corner frequency increases at a constant collector current density $J_{c}$ with temperature reduction. We also analyze the $f_{c}/f_{T}$ ratio that links Low Frequency Noise (LFN) with transistor speed, revealing good performance at cryogenic temperatures.By addressing the modeling of HBTs, that are the core active components of circuits used with quantum devices operating at deep-cryogenic temperatures, we believe that this study will be beneficial to designers of classical-quantum interfaces in emerging applications.