2. Length Matching:
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Ensure that each trace in a differential pair is of equal length, so signals arrive at the same time, preventing skew.
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The Length Tuning Tool allows you to fine-tune trace lengths to meet length-matching requirements, ensuring signal
timing alignment.
PCB Stackup Design
A well-planned stackup is critical in high-speed PCB design, as it directly impacts signal integrity, power distribution, and
EMI/EMC performance. In high-speed applications, stackup decisions determine how effectively signals are transmitted
across the board and how well the design manages interference and noise.
High-Level Overview of Stackup for High-Speed Designs
A typical high-speed PCB stackup includes multiple layers to support signal routing, power distribution, and grounding.
Common high-speed stackups are designed to optimize impedance control and minimize signal distortion. Here's an example
of a basic configuration used for high-speed designs:
OrCAD X Cross-section Editor displaying an 8-layer stackup configuration
1. Top Layer (Signal):
f
Used for high-speed signals and critical components.
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Directly above a ground plane to ensure controlled impedance.
2. Ground Plane:
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Placed directly beneath the top signal layer for shielding and to provide a stable reference for impedance.
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Essential for reducing EMI and crosstalk.
3. Internal Signal Layer1:
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Used for routing additional high-speed signals.
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Sandwiched between ground or power planes to form stripline structures, which enhance signal integrity.
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OrCAD X High-Speed Digital Design Guide
