Xilinx 7 Series User Manual

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Xilinx 7 Series User Manual Manual pdf 103 page image

7 Series FPGAs GTP Transceivers User Guide www.xilinx.com 103UG482 (v1.9) December 19, 2016TX Pattern Generator15. Deassert TXDLYEN for the master lane.16. Assert TXPHINIT for all slave lane(s). Hold this signal High until the rising edge ofTXPHINITDONE of the respective slave lane is observed.17. Deassert TXPHINIT for the slave lane in which the TXPHINITDONE is asserted.18. When TXPHINIT for all slave lane(s) are deasserted, assert TXPHALIGN for all slave lane(s).Hold this signal High until the rising edge of TXPHALIGNDONE of the respective slave laneis observed.19. Deassert TXPHALIGN for the slave lane in which the TXPHALIGNDONE is asserted.20. When TXPHALIGN for all slave lane(s) are deasserted, assert TXDLYEN for the master lane.This causes TXPHALIGNDONE of the master lane to be deasserted.21. Wait until TXPHALIGNDONE of the master lane reasserts. Phase and delay alignment for themulti-lane interface is complete. Continue to hold TXDLYEN for the master lane High to adjustTXUSRCLK to compensate for temperature and voltage variations.TX Pattern GeneratorFunctional DescriptionPseudo-random bit sequences (PRBS) are commonly used to test the signal integrity of high-speedlinks. These sequences appear random but have specific properties that can be used to measure thequality of a link. The GTP transceiver pattern generator block can generate severalindustry-standard PRBS patterns listed in Table 3-18.In addition to PRBS patterns, the GTP transceiver supports 16-UI or 20-UI square wave testpatterns, depending on data width as well as a 2-UI square wave test pattern and PCI Expresscompliance pattern generation (see Table 3-19 and Figure 3-16). Clocking patterns are usually usedto check PLL random jitter often done with a spectrum analyzer.Table 3-18: Supported PRBS PatternsName Polynomial Length ofSequence DescriptionPRBS-7 1 + X6 + X7 27 - 1 bits Used to test channels with 8B/10B.PRBS-15 1 + X 14 + X15 215 - 1 bitsITU-T Recommendation O.150, Section 5.3.PRBS-15 is often used for jitter measurementbecause it is the longest pattern the AgilentDCA-J sampling scope can handle.PRBS-23 1 + X 18 + X23 223 - 1 bitsITU-T Recommendation O.150, Section 5.6.PRBS-23 is often used for non-8B/10B encodingschemes. It is one of the recommended testpatterns in the SONET specification.PRBS-31 1 + X 28 + X31 231 - 1 bitsITU-T Recommendation O.150, Section 5.8.PRBS-31 is often used for non-8B/10B encodingschemes. It is a recommended PRBS test patternfor 10 Gigabit Ethernet. See IEEE 802.3ae-2002.Send Feedback