Teledyne LeCroy QPHY-PCIe - Manual (Page 24)

QPHY-PCIE Limit Sets
The default installation of QPHY-PCIE contains only one limit set, called PCIe 2.1 This set
contains all of the limits for PCIe 1.1a and PCIe 2.1.
Manual Deskewing Procedures
This section is only applicable to the oscilloscope and the cables connecting to the oscilloscope
channels. Note that the cables connecting the PeRT3 to the fixture or to the DUT must be
phase matched within a tight tolerance because the PeRT, like any generator, does not have the
capability to compensate for mismatched cables connected to its outputs.
Cable Deskewing Using the Fast Edge Output
The following procedure demonstrates how to manually deskew two oscilloscope channels and
cables using the fast edge output, with no need for any T connector or adapters. This can be
done once the temperature of the oscilloscope is stable. The oscilloscope must be warmed up
for at least a half-hour before proceeding. This procedure should be run again if the temperature
of the oscilloscope changes by more than a few degrees.
For the purpose of this procedure, the two channels being deskewed are referred to as Channel
X and Channel Y. The reference channel is Channel X and the channel being deskewed is
Channel Y.
1. Begin by recalling the Default Oscilloscope Setup.
2. Configure the oscilloscope as follows:
• Timebase
i.Fixed Sample Rate
ii.Set the Sample Rate to 40 GS/s
iii.Set the Time/Division to 1 ns/div
• Channels
i. Turn on Channel X and Channel Y.
ii. Set V/div for Channel X and Channel Y to 100mV/div.
iii. Set the Averaging of Channel X and Channel Y to 500 sweeps.
iv. Set the Interpolation of Channel X and Channel Y to Sinx/x.
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