PCB High-Speed Signal Design Guidelines: Agilex™ 5 FPGAs and SoCs

ID 821801
Date 11/18/2024
Public
Document Table of Contents

3.3.1. Impedance Tolerances

  • Strictly control the impedance tolerance of high-speed traces. Generally, ±10% can be used for stripline impedance, but ±7% is better.
  • Breakout routing usually has limited routing space which may cause impedance discontinuity. Optimize breakout routing trace geometries to reduce the impedance discontinuity for better return loss performance.
  • Microstrip channel loss may be higher, if the solder mask is lossy thus offsetting the benefit of low-loss PCB material. Microstrip channel generally has higher crosstalk compared to the stripline with the same spacing.