Impact of ballast resistor implementations on power performance of SiGe power HBTs

SiGe power HBTs integrated in SiGe BiCMOS with different ballast schemes are developed and compared in terms of large-signal power performance. Design considerations of ballast resistors for SiGe power HBTs are investigated for both common-emitter (CE) and common-base (CB) configurations. The investigation shows that emitter ballast resistors or base ballast resistors should be judiciously used for SiGe power HBTs operating at different frequencies and under different configurations in order to extract the best RF performance from these devices.