A DC-75-GHz Bandwidth and 54 dBΩ Gain TIA With 10.9 pA/ √Hz in 130-nm SiGe:C BiCMOS

A broadband low-noise amplifier with transimpedance (TI) feedback implemented in a 130-nm SiGe:C BiCMOS technology with f T of 300 GHz is presented. The circuit provides 22-dB gain and 75-GHz bandwidth while dissipating only 95 mW of power, achieving a gain bandwidth against dc power efficiency (GBW/P dc ) of 9.9 GHz/mW. Measured noise figure (NF) is 4 dB until 26.5 GHz, rising up to 6 dB at 70 GHz based on simulation. Ultrahigh data rate support is demonstrated with clear eye diagrams up to 100 Gb/s. Intended as a TI front end for optical receivers, the amplifier features 54-dBΩ TI gain with only 10.9 pA/√Hz averaged input-referred current noise density. Measured input-referred 1-dB compression point at 1 GHz occurs at -20 dBm input power. To the best of the authors' knowledge, the proposed amplifier exhibits the highest GBW/Pdc with the lowest NF reported to date, toward the next generation 400 Gb/s Ethernet.