Cryogenic performance of a 200 GHz SiGe HBT technology

The cryogenic performance of a 200 GHz SiGe HBT technology is presented for the first time. Measurements of the current-voltage, small-signal ac, and broadband noise characteristics of a 200 GHz SiGe HBT was made at 85K, 150K, 200K and 300K. At 85K, these SiGe HBTs maintain excellent dc ideality, with a peak current gain of 3800, a peak cut-off frequency of 250 GHz, and a minimum noise figure of approximately 0.30 dB at a frequency of 14 GHz, and in all cases represent improvements over their corresponding 300K values. These results suggest that aggressively-scaled SiGe HBT technology is well-suited for emerging cryogenic applications requiring extreme levels of transistor performance.