面向数据中心的超高速光模块板级信号完整性研究
Board Level Signal Integrity Study of Ultra-High-Speed Optical Module for Data Centers
钟光诚 1雷从彪 1姜宇轩 1谢亮1
作者信息
- 1. 中国科学院半导体研究所 光电子材料与器件重点实验室,北京 100083;中国科学院大学 材料科学与光电技术学院,北京 100049
- 折叠
摘要
[目的]人工智能的高速发展对数据中心算力提出了更高的要求.光模块作为数据中心光/电互连的核心器件,其设计也将迎来巨大挑战.随着光模块速率的不断提升,信号完整性问题成为制约光模块性能不可忽视的瓶颈.因此为了设计出满足数据中心光互连,特别是高性能计算场景速率要求的超高速光模块,需要对光模块内部高速链路进行优化设计.[方法]文章以一款双密度 4 通道小型可插拔(QSFP-DD)光模块设计方案为例,对光模块中影响信号完整性的因素进行了仿真优化.具体工作为,从理论角度分析了链路上引起信号完整性问题的部分,如过孔和球栅阵列(BGA)焊球,并讨论了优化这些性能的改进方法.特别是分析了针对 50 GHz以上频段信号传输的优化方法,使高速链路能实现超高速 4 阶电平脉冲幅度调制(PAM4)信号低损耗传输.另外,还研究了整体高速通道的传输性能,并利用 4 端口矢量网络分析仪进行了测试.[结果]研究结果表明,该设计方案能够达到所需的传输带宽并且能有效削弱谐振.全通道仿真结果显示所有通道传输带宽内回波损耗低于-15 dB,插入损耗低于 3 dB,可实现 224 Gbit/s PAM4 信号低损耗传输,同时测试结果与仿真结果基本相符,证明文章所提设计方案能满足数据中心高速光互连对光模块速率的需求.[结论]文章所提光模块信号完整性设计方法对今后超高速光模块设计具有重要的指导意义,同时也可以为其他各类高速电路设计提供参考.
Abstract
[Objective]The rapid development of artificial intelligence has put forward higher requirements for data center com-puting.As the core device of the data center optical interconnection,the design of optical module will also encounter big chal-lenges.With the increasing speed of optical modules,the signal integrity problem has become a bottleneck that restricts the performance of optical modules.In order to design a high-speed optical module that can meet the speed requirements of optical interconnects in data centers,especially high performance computing application,it is necessary to implement optimal design on the ultra-high-speed link inside the optical module.[Methods]In this paper,the factors affecting the integrity of the signal in the optical module are simulated and optimized with a Quad Small Form-factor Pluggable Double Density(QSFP-DD)optical module as an example.The specific work is to theoretically analyze the parts of the channel that may deteriorate the signal in-tegrity,such as vias and Ball Grid Array(BGA)solder balls,and discuss the optimization and improvement methods of these parts.In particular,this paper analyzes the optimization method for signal transmission in the frequency band above 50 GHz,so that the high-speed channel can realize the low-loss transmission for ultra-high-speed 4-Level Pulse Amplitude Modulation(PAM4)signal.In addition,the transmission performance of the whole high-speed channel is also studied and tested by the four-port vector network analyzer.[Results]The results show that the design scheme can achieve the required transmission bandwidth without resonance.The simulation results of full channel show that the return loss of all channels is less than-15 dB and the insertion loss is less than 3 dB,and 224 Gbit/s PAM4 signal low-loss transmission can be achieved.The test results are basically consistent with the simulation results,which proves that the design scheme can meet the requirement of high speed optical interconnects in Datacenters.[Conclusion]The method of signal integrity design of optical modules proposed in this paper has important guiding significance for the design of ultra-high-speed optical modules in the future,and will also pro-vide a reference for the design of other kinds of high-speed circuits.
关键词
数据中心光互连/高速电路/信号完整性/双密度4通道小型可插拔光模块/电磁仿真Key words
data center optical interconnects/high speed circuit/signal integrity/QSFP-DD optical module/electromagnetic simulation引用本文复制引用
基金项目
国家重点研发计划资助项目(2021YFB2206500)
出版年
2024
国家科技期刊平台
NSTL
万方数据