In Virtex-6 GTXtransceivers, the quad usage priorityrequires that GTX0 in Quad MGT 115be instantiated if any of the GTX transceivers are used in the application. This is becausethis quad contains theRCAL circuit that is requiredfor the internal termination resistors for all the transceivers.
Unlike Virtex-6 GTX, users do not have to follow any quad usagepriority in 7 series.For 7 series, the RCAL values are distributed at configuration whether the RCAL masteris instantiated or not. However, the RCAL master must be powered. Special care should be taken when using packages with multiple GT power planes because RCAL master is present only in one of the power planes. The GT power plane which has the RCAL master should always be powered.
In previous families there was only one GT which could be the RCAL master (MGT115). This changes for some devices in 7 series as you can have different columns of GTs or several SLRs. Each will have its own RCAL master which has to be powered as explained above.
Unlike the user guides of previous families, ug476 v1.4 does not state which GT is a RCAL master in the chapter for calibration explicitly yet. To find the RCAL master(s) for a specific device, you currently have to search for MGTAVTTRCAL pins in the package placement diagrams. This information should be added in v1.5.