An InPHBT common-base amplifier with tunable transimpedance for 40 Gb/s applications

This work features a 40Gb/s common-base transimpedance amplifier (TIA) design that employs electronically tunable transimpedance to compensate for various combinations of photo-detector and hybrid interconnect parasitics. A tuning transimpedance BW range of 10 GHz is demonstrated using this approach. Integrated with a 40fF photo-detector, the transimpedance amplifier achieves 62.3 dB-Ohm (1.3K-Ohm) differential transimpedance with a bandwidth of 39.3 GHz while consuming only 165 mW. This corresponds to a transimpedance-BW product per DC power of 310 ohms-GHz/mW. To the author's knowledge, this work is the first published demonstration of a tunable transimpedance amplifier for 40Gb/s applications, and is among the highest TZ-BWP per DC power reported for a 40Gb/s TIA.