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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
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)
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Sweeping Anti-pad Radius
Figure 39. Differential Return Loss and TDR Impedance Performances for 0201 AC Capacitors by Various Anti-pad SizesFigure shows a fixed rectangular GND cutout under the capacitors while changing only the signal via anti-pad radius.
Based on this TDR response, a larger via anti-pad eventually increases the impedance of the entire structure. Using a 22 mil anti-pad radius is an optimum solution for this case and results in the least mismatching.