Low-Noise Broadband CMOS TIA Based on Multi-Stage Stagger-Tuned Amplifier for High-Speed High-Sensitivity Optical Communication

Abstract

Constrained by the transimpedance limit, the conventional 1-stage shunt-feedback transimpedance amplifier (1S-SF-TIA) suffers poor noise and gain at higher data rates. In this paper, we propose to use a multi-stage stagger-tuned amplifier (MSTA) to constitute TIA (MSTA-TIA), which not only transcends the transimpedance limit of 1S-SF-TIA, but also realizes noise reduction in multiple fronts. First, the highgain MSTA enables 17X TIA gain over 1S-SF-TIA, which effectively suppresses the white noise. Second, the MSTA realizes at least 2.8X~1.6X lower noise than the conventional multi-stage amplifier, which is essential to form low-noise TIA since the amplifier noise usually dominates. Third, the TIA built upon the 3-stage STA also shows steeper out-of-band roll-off to enable high-frequency noise reduction. Overall, the MSTA-TIA achieves 6.9X and 1.9X noise power reduction over conventional singlestage and multi-stage SF-TIAs. As a demonstration, a 10 Gb/s optical receiver front-end prototype employing proposed MSTA-TIA topology is implemented in a standard 0.18μm CMOS technology. It achieves transimpedance gain of 68.3dBΩ, electrical bandwidth of 8.5GHz, and excellent input-referred noise current of 0.97μArms. The chip occupies 0.78 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> while consuming 43 mA from 1.8 V power supply. The low-noise design methodology in this paper empowers mature CMOS to compete with SiGe to make low-noise high-gain optical IC.