pci e电路板设计规范(内部资料)

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pci e电路板设计规范(内部资料)

pci express board design guidelines

1. Physical Interconnect Layout Design................................................ 5
1.1 Introduction ........................................................................................................ 5
1.2 Topology and Interconnect Overview .............................................................. 5
1.2.1 Card Interoperability ............................................................................................... 7
1.2.2 Bowtie Topology Considerations ............................................................................ 7
1.2.2.1 Lane Polarity Inversion.................................................................................................... 8
1.2.2.2 Lane Reversal and Width Negotiation ............................................................................. 8
1.3 Physical Layout Design Constraints............................................................... 11
1.3.1 PCB Stackup.......................................................................................................... 11
1.3.1.1 Desktop System Board and Add-in Card (4-layer) Stackup .......................................... 12
1.3.1.2 Server, Workstation and Mobile (6-layer, 8-layer and 10-layer) Stackups.................... 15
1.3.1.3 Add-in Card and Mobile (6-layer) Stackup ................................................................... 16
1.3.2 PCB Trace and Other Element Considerations ..................................................... 17
1.3.2.1 Differential Pair Width and Spacing Impacts ................................................................ 20
1.3.2.2 Differential Pair Length Restrictions and Budgets ........................................................ 23
1.3.2.3 Length Matching............................................................................................................ 24
1.3.2.4 Reference Planes............................................................................................................ 25
1.3.2.5 Breakout Area Specific Routing Guidelines .................................................................. 27
1.3.2.6 Edge Finger Design: Add-in Card ................................................................................. 29
1.3.2.7 Via Usage and Placement .............................................................................................. 30
1.3.2.8 Bends ............................................................................................................................. 32
1.3.2.9 Test Points and Probing ................................................................................................. 35
1.3.3 PCI Express Topologies ........................................................................................ 35
1.3.3.1 Interconnect Topologies for Two Components on the Baseboard ................................. 36
1.3.3.2 Interconnect Topologies for Baseboard with Add-in Card ............................................ 37
1.3.4 Passive Components and Connectors .................................................................... 38
1.3.4.1 AC Coupling Capacitors ................................................................................................ 38
1.3.4.2 Connectors ..................................................................................................................... 40
1.4 Summary........................................................................................................... 41

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