Power Performance Characteristics of SiGe Power HBTs at Extreme Temperatures

This paper presents the RF (6 GHz) power performance characteristics of SiGe power HBTs at cryogenic (77K) and high operation temperature (chuck temperature 120deg C, junction temperature up to 160degC). It shows that, without specific device optimizations for cryogenic operation, the power SiGe HBTs exhibit excellent large-signal characteristics at 77K. Comparing with room-temperature operation, similar power gain, output power and PAE were obtained when the devices were operated at the cryogenic temperature. The SiGe power HBTs also operate well at high junction temperature with reasonable power gain and output power degradations. The modeling of the SiGe power HBTs under high operation temperature indicates significant increase of base resistance (R_B) and emitter resistance (R_E) that account for the degradation of power performance of these devices.