Baseband to 140-GHz SiGe HBT and 100-GHz InP DHBT Broadband Triple-Stacked Distributed Amplifiers With Active Bias Terminations

This article describes the design and performance of a 140-GHz SiGe and a 100-GHz InP triple-stacked HBT distributed amplifier with active bias terminations. The active bias network is configured to extend the practical low-frequency operation while maintaining gain flatness and linearity. Triple-stacked HBTs are used to increase the gain-bandwidth and linear output capability. The SiGe design is based on HBTs with a peak f _T /f _max of 300/350 GHz and achieves 11.7 dB of gain and a bandwidth from baseband to 140 GHz. The InP HBT design is based on DHBTs with a peak f _T /f _max of 250/250 GHz and obtains a gain of 10.8 dB and a bandwidth of 100 GHz. Although the SiGe design achieves 1.5 times higher gain-bandwidth, the InP DHBT design achieves ~3-4.5 dB greater IP3, P1 dB, and P3 dB while consuming only ~23% higher dc power. These results represent the first broadband performance comparison of near-identical (apples-apples) DA designs implemented in SiGe and InP HBT device technologies. Although there are previous reports of larger bandwidth distributed amplifiers in both InP and SiGe technologies demonstrated up through 200 GHz, the InP and SiGe monolithic microwave integrated circuits (MMICs) described in this article are believed to represent the highest bandwidths reported for HBT DAs using practical on-chip active bias terminations.