线卡和背板上高速带宽传输的匹配端接通孔根(STUB)技术  

Matched terminated stub VIA technology for higher bandwidth transmission in Line cards and backplanes

作　　者：吴小龙[1] 吴梅珠[1] 

机构地区：[1]江南计算技术研究所,江苏无锡214083

出　　处：《印制电路信息》2011年第6期22-27,40,共7页Printed Circuit Information

摘　　要：线卡和底板中的通孔支线(短截线)固有阻抗不匹配问题对于要获得更高传输带宽来说是一个很大的阻碍。本篇论文对高层数PCB短的和长的通孔支线进行了研究。数据分析表明:长支线会产生更大的反射损失和S21特性的侵蚀。短支线会产生预期外的相位变化,并带来更大的谐波侵蚀脉冲波形和闭合眼图。通过使用顺序层压和背钻方法可以使这些阻碍得到解决,但会导致更高的产品成本。对于线卡,更密集通孔和隔离盘尺寸使背钻困难异常且难以操作。就高成本的根部背钻方面来说,已发表的匹配端接通孔支线的MTSvia?技术可作为一种替代方法,并可应用到线卡和底板之上。制作埋入式端接电阻用于去除接地层反射并降低串扰和额外的损失。3D电磁场模拟被用于计算S11,S21参数,特性阻抗和眼图。制作参考底板是当前用于确认时间和频率范围内的测量的模拟结果。For in line cards and backplanes the inherent impedance mismatch of via stub is a significant impediment to obtaining higher transmission bandwidth. This work examines short and long via stubs for high layer count printed circuit boards. Data analysis shows long stubs give significant reflection losses and corruption of the S21 characteristics. Short stubs give undesirable phase shift for higher harmonics corrupting pulse shape and closing eye patterns. These obstacles have been circumvented by using sequential lamination stackups and back drilling production methods resulting in higher product cost. For in line cards, the tighter dimensions on vias and anti-pads make back drilling difficult to impossible. A matched terminated stub MTSvia^TM technology is presented as an alterative approach to the high cost of stub back drilling and can be applied to lines cards and backplanes. An embedded resistor is used as a terminator to rout reflections to ground and suppress crosstalk and additional losses. 3-D electromagnetic simulation is used to calculate S11, S21 parameters, characteristic impedance and eye patterns. Reference backplanes are currently being fabricated to verify simulation results in time and frequency domain measurements.

关 键 词：通孔 支线(短截线) 模拟 MTS电阻设计 

分 类 号：TN41[电子电信—微电子学与固体电子学]