基于联合时钟恢复和均衡技术的光互连信号处理方法

Digital signal processing method for optical interconnect based on joint clock recovery and equalization

在数据中心光互连系统中,针对时钟恢复模块和均衡模块相互依赖而导致两模块先决条件冲突的问题,提出了联合均衡和定时恢复反馈环路的数字信号处理方案。该方案针对PAM4信号特征,采用了改进的Gardner反馈式全数字时钟同步算法,以降低时钟恢复误差、提高收敛性能;在均衡模块,提出并采用了一种基于T/2分数间隔的改进级联多模盲均衡算法,以减小均衡稳态误差、改善信号均衡效果。仿真结果表明,该联合方案能够降低系统误码率,在满足硬判决前向纠错阈值下,40 km传输后的接收机灵敏度为-16 dBm,相较于级联方案提升了至少3 dBm。同时,联合方式的抗抽样时钟偏移(SCO)的能力更强,最大能容忍的SCO提高约200个时钟偏移量,说明本方案可以有效补偿线性损伤和时钟误差。

In the Optical interconnect system of data center,a digital signal processing scheme for joint equalization and timing recovery feedback loops is proposed to address the issue of conflicting prerequisites between the clock recovery module and equalization module due to their interdependence.This scheme adopts an improved Gardner feedback all digital clock synchronization algorithm based on the characteristics of PAM4 signals to reduce clock recovery errors and improve convergence performance;In the equalization module,an improved cascaded multimodal blind equalization algorithm based on T/2 fractional interval was proposed and adopted to reduce steady-state error and improve signal equalization performance.The simulation results show that this joint scheme can reduce the system error rate.Under the condition of meeting the hard decision forward error correction threshold,the receiver sensitivity after 40 km transmission is-16dBm,which is improved by at least 3dBm compared to the cascaded scheme.Meanwhile,the joint approach has a stronger ability to resist sampling clock offset(SCO),with a maximum tolerable increase of approximately 200 clock offsets,indicating that this scheme can effectively compensate for linear damage and clock errors.