AN 766: Intel® Stratix® 10 Devices, High Speed Signal Interface Layout Design Guideline

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ID 683132
Date 3/12/2019
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Document Table of Contents
Document Table of Contents x
Intel® Stratix® 10 Devices, High Speed Signal Interface Layout Design Guideline
Intel® Stratix® 10 Devices, High Speed Signal Interface Layout Design Guideline x
Intel® Stratix® 10 Devices and Transceiver Channels PCB Stackup Selection Guideline Recommendations for High Speed Signal PCB Routing FPGA Fan-out Region Design CFP2/CFP4 Connector Board Layout Design Guideline QSFP+/zSFP/QSFP28 Connector Board Layout Design Guideline SMA 2.4-mm Layout Design Guideline Tyco/Amphenol Interlaken Connector Design Guideline Electrical Specifications Document Revision History for AN 766: Intel® Stratix® 10 Devices, High Speed Signal Interface Layout Design Guideline
FPGA Fan-out Region Design x
Signal Break-out Recommendations FPGA Fan-out Region Routing Recommendations AC Coupling Capacitor Layout and Optimization Guidelines
Signal Break-out Recommendations x
Option 1: Via-In-Pad Topology Option 2: Dog-bone with GND Cutout at BGA Pad Topology Option 3: Micro-via Topology GND Cutout Under BGA Pads in Fan-out Configuration Comparison of Dog-bone with GND Cutout Under the BGA and Via-in-Pad Configurations Trace Shape Routing at the BGA Void Area (Tear Drop Configuration)
FPGA Fan-out Region Routing Recommendations x
Comparison of Conventional and Recommended Break-out Routing Topologies
Comparison of Conventional and Recommended Break-out Routing Topologies x
Conventional Jog-out Routings with Skew-matching Right After Break-out The Impact of Via Height and Via Anti-pad Over Insertion Loss
AC Coupling Capacitor Layout and Optimization Guidelines x
0201 AC Capacitor 0402 AC Capacitor PCB AC Capacitor Placement Layout Recommendation
0201 AC Capacitor x
Sweeping Anti-pad Radius Sweeping Void Width only on the First GND Plane Under the Capacitor
0402 AC Capacitor x
Sweeping Anti-pad Radius Sweeping Void Width Only on the First GND Plane under the Capacitor Adding a Trace Reference to the 0201 AC Capacitor Adding a Trace Reference to the 0402 AC Capacitor
PCB AC Capacitor Placement Layout Recommendation x
What to Avoid for AC Capacitor Configuration
CFP2/CFP4 Connector Board Layout Design Guideline x
CFP2 Host Connector, Module Assembly, and Pinout CFP4 Host Connector, Module Assembly, and Pinout Recommended PCB Design Guideline at the CFP2/CFP4 Connector CFP4 Design Example and Optimization Performance
CFP4 Design Example and Optimization Performance x
CFP4 Connector Layout: Signal Via, Trace Routing Impact, and Optimization Two Different Break-out Routings at the CFP4 Connector Area CFP4 Connector Routing Topologies Design Example Full CFP4 Channel Analysis Design Example (Excluding the Connector) CFP2 Connector Area Layout
QSFP+/zSFP/QSFP28 Connector Board Layout Design Guideline x
QSFP+ Module Assembly and Pinout Recommended PCB Design Guideline for QSFP+/zQSFP/QSFP28 Channels Recommended QSFP+ Signal Routing QSFP28 Example Design and Performance Optimization
SMA 2.4-mm Layout Design Guideline x
SMA 2.4 mm Molex® Connector Assembly PCB Design Guidelines for Channels Using the 2.4 mm Connector 2.4 mm Example Design Performance
PCB Design Guidelines for Channels Using the 2.4 mm Connector x
Recommended PCB layout Design for Version-A SMA 2.4 mm Connector Recommended PCB layout Design for Version-B SMA 2.4 mm Connector Performance Comparison between Option1 and Option2 layout Other 2.4 mm Connectors 2.4 mm Channel Specifications
Tyco/Amphenol Interlaken Connector Design Guideline x
Connector Signal and Pin Assignment
Connector Signal and Pin Assignment x
PCB Design Guidelines for Channels with 25 Gbps + Interlaken Interface Connector Recommendations Interlaken Channel Interface Performance Example
Electrical Specifications x
CEI 28 Very Short Reach (VSR) Specifications for CFP2/CFP4/QSFP+/QSFP28/zQSFP/SMA 2.4 mm Interlaken Interface Specification
Intel® Stratix® 10 Devices, High Speed Signal Interface Layout Design Guideline

FPGA Fan-out Region Routing Recommendations

Intel recommends that you use a 95 Ω differential trace lane for both PCB and fan-out region routing. The tolerance of trace impedance can be within ±10% on the PCB.

The back-jog routing configuration is best for high speed signals. The advantage of the back-jog configuration is that it keeps the skew matching for both differential lanes in the break out region. Back-jog routing can be either single-ended back-jog or neck-down with back-jog in the fan-out region.

Figure 14. Recommended Single-ended Back-jog and Differential Neck-down with Back-jog Break-out Routing

Simulations and measurements show that a traditional jog-out routing configuration in the break-out region degrades performance, specifically for return loss. The traditional jog-out routing requires skew-matching right at the device edge.

Figure 15. Conventional In-line Break-out and Differential Neck-down with Jog-out Break-out Routing

For signal data rates above 15 Gbps, Intel recommends that you use a back-jog break-out routing configuration. For data rates lower than 15 Gbps, you must use the jog-out break-out routing with skew matching at the device edge.

For both of these options, single ended routing in the fan-out region results in better insertion loss performance.

Observe these guidelines when routing in the fan-out region:

  • Route one signal pair between 1 mm BGA pitch for maximum isolation between pairs.
  • Keep the fan-out routing length less than 1 inch.
  • Avoid routing lanes which are close to the edge of the void area. Maintain enough space between the trace edge and the void edge. A wide reference plane is always required for any high speed signal routing.
Figure 16. Example of Routing Away from the Void AreaThe a and b space dimensions must be no smaller than the size of the trace width.
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