反焊盘设计及其对差分过孔高频特性影响分析

Antipad Design and Its Influence on High Frequency Characteristics of Differential Vias

随着差分信号速率的不断提升,差分过孔对高速差分信号的信号完整性影响越来越不可忽视。针对差分过孔在高速PCB中低反射、高传输和阻抗稳定的设计要求,通过等效过孔模型进行反焊盘预估计算,并根据估算值对不同形状的差分过孔反焊盘进行了仿真和分析。采用HFSS软件对16层PCB中的差分过孔进行了三维建模和仿真,并利用Designer软件对模型进行了仿真和眼图分析。结果表明在一定的频率范围内,反焊盘面积越大,差分过孔高频特性越好。

With the improvement of the differential signal rate, the influence of differential vias on the signal integrity of the high-speed differential signal is more and more noticeable. Mining at the design requirements of low reflectance, high-transmission and stable impedance of differential vias in high-speed PCB, the antipad prediction was calculated by equivalent vias model. According to the estimated value, different shapes of differential vias antipad were simulated and analyzed. Differential vias in a 16-layer PCB were modeled in 3D and simulated with HFSS, and the model was simulated and analyzed in eye diagram with software of Designer. The results showed that the larger the area of antipad in a certain frequency range, the better the high frequency characteristics of the differential vias.