Abstract: 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. Aiming 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.

Key words: integrity of signal, antipad, differential vias, high-frequency characteristics, eye diagram