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

Abstract

This paper reports on the design and linearity performance characteristics of a DC-140GHz SiGe and a DC- 100GHz InP triple stacked HBT distributed amplifier with active bias terminations. The active bias topology is configured to extend the practical low frequency operation while maintaining gain- flatness and linearity. Triple stacked HBTs are used to increase the supply and linear output capability. The SiGe design is based on HBTs with an fT/fmax of 300/350GHz and achieves 11.7 dB and bandwidth from baseband to 140GHz. The InP HBT amplifier is based on DHBTs with fT/fmax of 250/250GHz and achieves a gain of 10.8dB and a bandwidth of 100GHz. While the SiGe design achieves 1.5 higher gain-BW, the InP DHBT MMIC achieves ~3- 4.5dB greater IP3, P1dB, and P3dB while consuming only ~23% higher dc power. This is believed to be the first broadband linearity benchmark comparison reported between SiGe and InP HBT technologies using near identical DA designs. Although there are previous reports of larger bandwidth distributed amplifiers in both InP and SiGe technologies demonstrated up through 200GHz and summarized in [8], the InP and SiGe MMICs of this work are believe to be the highest bandwidths reported for triple stacked HBT DAs using practical on-chip active bias terminations.