A 145-GHz-Bandwidth InP-HBT Active Combiner Module Enabling 448-Gbps PAM-4 Signal Generation

This paper presents a 145-GHz-bandwidth active combiner module with 0.8-mm-coaxial-connector interfaces and integrated DC-block functions for ultra-high-speed signaling applications with a symbol rate of 224-GBaud and beyond. The active combiner IC featuring a bandwidth of over 150 GHz and adequate peaking characteristics aiming for packaging-loss compensation was designed and fabricated using 250-nm InP HBTs with the$f_{\mathrm{T}}/f_{\max}$of 460/480 GHz. The ultrabroadband package equipped with 0.8-mm coaxial connectors and a quartz glass substrate was developed to modularize the active combiner IC. DC-block functions based on silicon capacitors were also integrated into the package to improve connectivity with other devices. Using the fabricated active combiner module, a 224- GBaud PAM-4 signal with a bit rate of 448-Gbps was successfully generated. This is the first demonstration of an active combiner module featuring a 145-GHz bandwidth and built-in DC-block functionalities.