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AR# 64293

High Speed SelectIO Wizard - If using a Serialization Factor of 4, the Interface Data Speed is limited to 800Mbps


When using a Serialization Factor of 4, the Interface Data Speed is limited to 800Mbps, even though the fabric can run fast enough to allow an Interface Data Speed of 1600Mbps.


To work around this issue you can use the High Speed SelectIO to set up everything else that is required for your interface and generate the output products. 

Then replace the .XCI file with the <<component name>>.v and other required files. 

The constraints will also need to be added.

They can be found in the <<component name>>.xdc file.

Note: the port names may need to be changed.


To change the interface speed you need the change the rate that the PLL is running at.

The PLL instantiation should be found in the <<component name>>_hsio.v file.

The CLKOUTPHY_MODE attribute defines the Frequency of the CLKOUTPHY (VCO, VCO_2X, VCO_HALF). 

Ensure that for the speed grade you are using, you have a VCO within the Fvcomin = 600 and  Fvcomax = 1200. 

So you could run the VCO at 625MHz and use VCO_2X to get the 1250MHz.

You'll also need to change the REFCLK_FREQUENCY of the BITSLICEs.

Please refer to (Xilinx Answer 64216) High Speed SelectIO - Known Issue List for the software version that the issue is resolved in.

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
64216 High Speed SelectIO Wizard - Known Issue list N/A N/A
AR# 64293
Date 05/15/2015
Status Active
Type General Article
  • Kintex UltraScale
  • Virtex UltraScale
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