Broadband and Compact 112 Gbit/s Transimpedance Amplifier in a SiGe Copper Backend Technology

In this paper, an ultra broadband and compact transimpedance amplifier fabricated in the novel high performance 130 nm IHP SG13G3 copper backend technology, featuring f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</inf>/f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> of 470 / 650 GHz, is presented. The amplifier is composed of three stages, an input stage with a standard shunt-shunt feedback topology, used to obtain a compromise between speed, noise and gain, a current-steering variable gain amplifier and a cascode, used as a buffer, at the output. Inductive peaking techniques have been employed to increase the bandwidth and flatten the frequency response, while degeneration networks have been used to improve the linearity of the circuit. Measurement results show that the proposed design has a low frequency transimpedance gain of 50 dBΩ, a $28.1{\text{pA}}/\sqrt {{\text{Hz}}} $ at 115 GHz of noise current density and a 3dB bandwidth of more than 115 GHz, along with a total harmonic distortion at 1 dB compression point of 4 %, in band group delay variation of ±1.5ps and an overall power dissipation of 165 mW at nominal conditions. Time domain measurements show operation up to 112 Gbps non-return-to-zero. To the authors’ knowledge, the presented design shows one of the largest operating bandwidth in SiGe BiCMOS technology compared to the state-of-the-art works that can be found in the literature.