A Low-Noise Design Technique for High-Speed CMOS Optical Receivers
A Low-Noise Design Technique for High-Speed CMOS Optical Receivers
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DOI：
10.1109/jssc.2014.2322868
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发表时间：
2014-05
影响因子：
5.4
通讯作者：
Dan Li;Gabriele Minoia;M. Repossi;D. Baldi;E. Temporiti;A. Mazzanti;F. Svelto
中科院分区：
文献类型：
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作者：
Dan Li;Gabriele Minoia;M. Repossi;D. Baldi;E. Temporiti;A. Mazzanti;F. Svelto
这项工作对实现低噪声宽带 TIA 的替代拓扑进行了仔细比较。为了打破噪声和带宽之间的权衡，所提出的前端使用两级，即低噪声窄带互阻抗接口，后面是旨在恢复所需带宽的均衡器。该技术对于白噪声分量特别有效。核心第一级放大器利用电流复用来实现最低功耗，并针对有色噪声降低进行了优化。与基于相同带宽的传统并联反馈 TIA 的设计方法相比，净噪声功率降低了 4 倍。一个完整的接收器，连接商用光电二极管，并包括所提出的两级前端（TSFE）、限幅放大器和宽带输出缓冲器，已在 65 nm CMOS 中实现。针对100GBASE-LR4标准定制的光通信，该标准指定用于通道速率为25 Gb/s的中长距离传输。实现的原型在 BER 为 10-12 时显示出 -11.9 dBm 的灵敏度，采用 PRBS31 输入模式，跨阻增益为 83 dBΩ，同时可承受 160 fF 的总输入电容。据作者所知，这是 CMOS 中 25 Gb/s 光接收器实现的最佳灵敏度性能，可与最先进的 BiCMOS 实现相媲美。
A careful comparison between alternative topologies to realize low-noise wideband TIAs is carried out in this work. In order to break the tradeoff between noise and bandwidth, the proposed front-end uses two stages, i.e. a low-noise narrowband transimpedance interface followed by an equalizer aimed at restoring the required bandwidth. The technique is especially effective for white noise components. The core first-stage amplifier exploits current reuse for minimum power consumption and is optimized for colored noise reduction. A net 4 × noise power reduction is achieved if compared with a design approach based on a traditional shunt-feedback TIA with the same bandwidth. A complete receiver, interfacing a commercial photodiode, and including the proposed two-stage front-end (TSFE), a limiting amplifier and a wideband output buffer has been realized in 65 nm CMOS. Optical communications tailored to 100GBASE-LR4 standard, which is specified for mid-to-long range transmissions at a channel rate of 25 Gb/s, are targeted. Realized prototypes show a sensitivity of -11.9 dBm at a BER of 10-12 with a PRBS31 input pattern and a transimpedance gain of 83 dBΩ, while tolerating an overall input capacitance of 160 fF. To the best of the authors' knowledge, this is the best sensitivity performance achieved by 25-Gb/s optical receivers in CMOS, comparable to state-of-the-art BiCMOS realizations.