InP/GaAsSb DHBTs: THz Analog Performance and Record 180-Gb/s 5.5Vppd-Swing PAM-4 DAC-Driver

• Published in: 2022 IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium (BCICTS) pp. 112 - 119
• Main Authors: Bolognesi, C. R., Arabhavi, A. M., Hersent, R., Hamzeloui, S., Jorge, F., Wen, X., Riet, M., Luisier, M., Nodjiadjim, V., Ciabattini, F., Mismer, C., Ostinelli, O., Konczykowska, A.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 16-10-2022
• Subjects: Analog/Digital Circuits; Double heterojunction bipolar transistors; InP/GaAsSb; Linear Driver; Modulation; Performance evaluation; Power amplifiers; Power Amplifiers (PAs); Power demand; Power dissipation; Pulse-Amplitude Modulation Format (PAM-4); Transistors; Type-II DHBTs
• ISSN: 2831-4999
• DOI: 10.1109/BCICTS53451.2022.10051763

"Type-II" InP/GaAsSb DHBTs are the first non-GaInAs -based transistors to show oscillation frequencies > 1 THz with the associated benefits of higher breakdown voltages, low power dissipation, and superior linearity and scaling characteristics. Whereas no large-signal characterization of THz transistors is found in the literature, THz InP/GaAsSb DHBTs display attractive 94 GHz load-pull characteristics, and less aggressively scaled devices achieve record saturated output power and output power density per unit emitter area. The physical advantages of Type-II InP/GaAsSb are reviewed here. Beyond impressive analog small/large-signal performance metrics, we report a record mixed-signal performance for a PAM-4 DAC-driver designed and fabricated at III-V Lab in a 0.7-μm InP/GaAsSb DHBT technology implemented on epitaxial layers grown at ETHZ. The DAC-driver offers an unprecedented 5.5-Vppd 90-GBd (180 Gb/s) differential output swing with high eye diagram quality and over 12-dB gain control capability at a 1.1-W power consumption, leading to a record 3.1-GBd E/O modulator driver figure-of-merit (FoM). PAM-4 operation at 112-Gb (224 Gb/s) is also demonstrated with 3.35-Vppd and 0.6-W dissipation, also with a record 2.6-GBb E/O FoM. A 110 GHz bandwidth linear driver with a 16.7 dB gain and 0.85-W consumption was also implemented in the same technology, enabling a 4.1-Vppd output swing at 100 Gb/s both in PAM-4 and NRZ signaling. The all-around outstanding performance of InP/GaAsSb DHBTs makes them attractive for a wide variety of analog and mixed-signal circuit blocks used in modern telecommunication applications.