AN 766: Intel® Stratix® 10 Devices, High Speed Signal Interface Layout Design Guideline

ID 683132
Date 3/12/2019
Document Table of Contents

Sweeping Anti-pad Radius

Figure 41. Differential Return Loss and TDR Impedance Performances for 0402 AC Capacitors by Various Anti-pad SizesFigure shows a fixed rectangular GND cutout under the capacitors while changing only the signal via anti-pad radius.

The large via anti-pad increases the impedance of the structure. Using a 22 mil via anti-pad is an optimum solution for the 0402 capacitor and results in the least mismatching with the rest of the system.