高速可插拔光互连模块中信号的完整性设计

Signal Integrity Design for High Speed Pluggable Optical Transceiver

给出了一款双向4路并行14Gb/s光收发器的物理设计。分析了链路上的信号完整性设计,考虑了各个物理结构中不连续点,如差分过孔、AC耦合电容、金丝绑线、可插拔I/O接口,对传输特性的影响。从理论上分析了S参数谐振现象,找出导致谐振的原因,给出了用于分析此类问题的理论公式。通过对多种不连续结构进行电磁仿真和结果对比,提出具体的性能改进方案。通过整个链路的阻抗控制,插入损耗在10-15GHz内提高了1dB,S参数的谐振得到明显改善。最后,从时域的TDR和眼图测试角度对优化结构进行了验证。

Electrical design and test of a bi-directional 4×14Gb/s optical transceiver was presented.Design of signal integrity in the channel was analyzed,with effects of discontinuous structures,such as vias,coupling capacitors,bond wires and I/O pins in the high speed channels,taken into consideration.Theoretical analysis of S parameter resonance was made to find out the reason for this phenomenon,and guiding rules for further simulation and optimization were provided.Different discontinuous structures were simulated and compared to formulate strategies for performance improvement.With good impedance control,insert loss of transmission channel was improved by 1dB in the frequency range from 10 GHz to 15 GHz,and S-parameter resonances were largely mitigated.Finally,the optimization work was verified with experimental tests of TDR and eye diagram in time domain.