Part 2: Practical Example - Constraint Management for High-Speed Designs
Welcome to the second part of this high-speed digital design guide. To solve common high-speed issues in printed circuit
boards we have general rules and recommendations, but the most important aspect is practical application.
Use Part 1 of the guide as a reference and reminder for what you can do to reduce problems in high-speed PCB.
In this guide, we will show you how to implement high-speed constraints in a practical design. The guide will focus on appli-
cation, specifically for high-speed timing considerations, with references to signal integrity, EMI, power integrity, the power
distribution network and more relevant topics for creating a successful PCB layout.
We will not cover every signal but just enough to explain how to implement the critical steps for a high-speed PCB layout. The
entirety of the design is left as an exercise for the reader.
To access the project files used in this guide click this link: HSD_FPGA.zip
Project Overview
This high-speed design project centers around an FPGA interfacing with DDR memory, specifically:
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FPGA: XC6SLX25-3FTG256I
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DDR3 Devices:
ɢ UPD431000AGW-B15
ɢ MT41J512M4JE-15E:A
Key Design Parameters
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DDR Interface: 300-800 MHz
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Crosstalk Limit: 8% for critical signals
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Manufacturing Capabilities:
ɢ High-speed traces: 4 mil minimum
ɢ Standard traces: 6 mil minimum
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OrCAD X High-Speed Digital Design Guide
