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

ID 683132
Date 3/12/2019
Document Table of Contents

CFP2 Connector Area Layout

These are the differential TDR results from simulation including the PCB portion connected to the CFP2 connector and host compliance board. The TDR result is based on the following configuration:

  • No GND cutout
  • One single GND layer cutout
  • Two GND layer cutouts below the CFP2 high speed signal pads

The host PCB routing has a 100 Ω impedance.

Figure 71. Simulation Structure of Partial HCB, CFP2 Connector, and Host PCB with TDR Differential Impedance ResultsThe TDR differential impedance results are from the host PCB while the HCB port is terminated.

The following figure shows the actual measured differential TDR on an Intel® Arria® 10 device populated SI board for CFP2 full channel. Two GND layers are cut out below the high speed connector pads. The reduced differential impedance is approximately 8.5 Ω at the CFP2 connector transition to the PCB.

Figure 72.  Intel® Arria® 10 device PCB Layout at the CFP2 Connector
Figure 73. TDR Differential Impedance for Intel® Arria® 10 device CFP2 Full Channel Including CFP2 Connector and HCB
Figure 74. Insertion and Return Loss Performances of the Intel® Arria® 10 device CFP2 ChannelThis figure uses the example in Figure 72 with bare host board only.

Measured SP performances for one single TX pair and one single RX pair which both meet the CFP2 specification.