超高速SiGe BiCMOS光接收机前端电路低噪声设计方法研究

高带宽是光接收机高速传输的基本要求，而低噪声则是衡量光接收机性能的最核心指标。传统的光接收机前端电路中，决定系统噪声性能的前置放大器一般采用基于并联反馈结构的跨阻放大器。随着电路带宽要求进入数十GHz领域，这种经典结构日益受限于其内在的跨阻约束，噪声性能随带宽增加而迅速下降。为解决这一问题，本项目旨在探索以低带宽跨阻放大器加带宽均衡器的新型两级结构：通过将噪声和带宽目标分离，以先解决噪声后解决带宽的方式，打破一级结构中的跨阻约束限制，最终实现低噪声和高带宽目标。同时，在晶体管级电路层面，引入各个噪声源的多元优化，配置电路设计最优参数，进一步优化噪声。最后，为保证系统在各种条件下的最佳工作状态，引入增益自动控制环路、均衡器自适应环路和直流失调消除环路。系统将采用较深亚微米CMOS成本更低的SiGe BiCMOS来设计，最终实现一种高性能、低成本、高集成度的低噪声光接收机前端电路设计。

Large bandwidth guarantees high-speed transmission of optical receivers, while low noise fundamentally set tones of the receiver performance. In conventional implementation of optical receiver circuits, the pre-amplifier that determines the noise performance usually adopts shunt-feedback-based transimpedance amplifiers (TIA). As bandwidth requirements go into tens-of-GHz range, this structure suffers from its intrinsic Transimpedance Limit, leading to noise deterioration as bandwidth keeps going high. To solve this problem, this project explores a new architecture comprising a low-bandwidth TIA followed by a bandwidth equalizer. By separating noise and bandwidth targets, solving noise first and bandwidth later, Transimpedance Limit can be effectively circumvented while eventually satisfying both noise and bandwidth requirements. Meanwhile, in transistor circuits level, multiple noise sources will be optimized together to help configure core design parameters and achieve further improved noise. Finally, to secure receiver performance under various conditions, three different feedback loops, namely AGC loop, equalization adaptation loop and DC offset cancellation loop will be introduced. The optical receiver will be realized in SiGe BiCMOS rather than expensive advanced CMOS for lower cost, and ultimately enabling low-noise design with overall optimum performance, cost and integration.