AN 958: Board Design Guidelines

ID 683073
Date 6/26/2023
Document Table of Contents
Give Feedback Termination Schemes

Mismatched impedance causes signals to reflect back and forth along the lines, which causes ringing at the load receiver. The ringing reduces the dynamic range of the receiver and can cause false triggering. To eliminate reflections, the impedance of the source (ZS) must equal the impedance of the trace (Z0), as well as the impedance of the load (ZL). Stratix® devices feature support for on-chip implementation of a termination resistor. This section discusses the following signal termination schemes:
  • Simple parallel termination
  • Thevenin parallel termination
  • Active parallel termination
  • Series-RC parallel termination
  • Series termination
  • Differential pair termination
  • On-chip termination