PCIe Design Guide (Gen 4, 5, 6)

You can download the guide for the engineers building High-Speed PCB Systems:

Contents

Part 1

Routing & Stackup

1. How do vias affect high-speed PCIe signals?
2. How do pad sizes and anti-pad geometries affect via performance?
3. What trace separation rules should be followed?
4. What are best practices for breakout routing in BGA packages?
5. PCIe lanes, and how is it calculated?
6. What routing topologies are recommended for PCIe lanes?
7. How are connectors and card-edge interfaces designed to maintain signal integrity in PCIe?
8. How does stackup design affect PCIe performance?
9. What design rules apply to 8-layer stackups for Gen6 routing and isolation?
10. What is reference plane stitching and why is it important?
11. How are backplane or multi-board PCIe channels handled?
12. Where should AC coupling capacitors be placed?
13. What layout priorities are critical for PCIe Gen6?
    Loss & Materials
14. What is insertion loss, and what mechanisms cause signal attenuation in PCIe?
15. What PCB materials are suitable for PCIe Gen4, Gen5, and Gen6?
16. How does copper roughness affect insertion loss at Gen6 speeds?
17. How do you manage material transitions between different boards (e.g., FR4 ↔ low-loss)?
    Equalization & Channel Modeling
18. How does PCIe receiver equalization work?
19. What are PCIe equalization presets and test modes?
20. What’s the difference between CTLE and DFE equalization?
21. How is equalization different in PCIe Gen6?
22. What are redrivers and retimers, and how do they differ?
23. When should you choose a redriver verse a retimer in PCIe systems?
24. How do you validate retimer operation and configuration in a PCIe link?
25. How should redrivers and retimers be placed?
26. How is margining performed in PCIe Gen4/Gen5/Gen6?
27. How is Channel Operating Margin (COM) calculated and interpreted for Gen6 compliance?
    PCIe Design Guide – Content References

Browse and download part 1:

Part 2

Planned content

Simulation & Validation

28. How can simulation help predict real-world performance?
29. What is the role of IBIS-AMI models in simulation?
30. How accurate are IBIS-AMI models in predicting behavior?
31. What simulation strategies are best for PCIe channels?.5
32. How should simulation and measurement results be reconciled?
33. How should vias be modeled for accurate signal integrity?
34. How does spread spectrum clocking (SSC) impact PCIe link margin and simulation accuracy?
35. What are PCIe eye diagram specifications?
36. What measurement tools validate high-speed PCIe layout?
37. How is eye height and width measured at the receiver?.
38. What are best practices for modeling and stitching S-parameters in multi-board PCIe systems?
39. How should signal integrity be validated under process-voltage-temperature (PVT) variation?
    Signal & Power Integrity Fundamentals
40. What causes signal reflections, and how are they managed?
41. How do edge rates (rise/fall times) affect signal integrity?
42. How does trace geometry impact signal integrity?
43. Why is reference plane continuity crucial in PCIe?
44. What is skew, and how does it impact PCIe differential signaling?
45. What is crosstalk, and how can it be minimized in PCIe layout?
46. How much spacing is needed between differential pairs to avoid crosstalk?
47. What challenges does PAM4 introduce in PCIe Gen6?
48. How do modal conversions affect Gen6 PAM4 signals and how can they be detected?
49. How do voltage ripple and PDN impedance affect PCIe receiver eye margin?
50. How does power integrity affect PCIe signal integrity?
51. What thermal design considerations affect PCIe signal integrity and reliability?
    Clocking, Reset, and Compliance
52. What are the layout and isolation requirements for PCIe reference clocks?
53. What are SRNS, SRIS, and DC architectures for PCIe reference clocks?
54. How is the PCIe LTSSM useful in debugging link issues?
55. How can LTSSM failures be debugged at the system level?
56. How do system resets and power sequencing impact PCIe link initialization?
57. How does PCIe link training work, and how can equalization issues be debugged during initialization?
58. What is PCIe compliance testing, and how is it performed?
59. What clock jitter and SSC constraints apply for SRIS and Gen6 PLL lock?
60. What should be included in a PCIe final sign-off checklist?
    PCIe Design Guide – Content References

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