Removing Oscilloscope Noise from PCIe 6.0 Compliance Pattern Measurements

Figure 1. The new SDAIII-PCIE6 option offers
three methods for removing oscilloscope noise
from PCIe 6.0 Compliance Pattern measurements
as required by the standard.

The new SDAIII-PAMx and SDAIII-PCIE6 options for Teledyne LeCroy oscilloscopes enable you to quickly make new PCIe 6.0 noise measurements SNDR and RLM with the oscilloscope baseline noise removed, as required by the standard.

Here's a brief description of the three, proprietary noise removal methods from which you can choose.

Manual Method

Manual uses the specified amount of oscilloscope noise for the 𝜎scope variable in the SNDRnr formula (described in the last post). This method is useful if you have previously measured your oscilloscope baseline noise and know what value to enter.

New PCIe 6.0 Compliance Pattern Measurements

PCI Express® 6.0 features significant changes from PCIe® 5.0. In particular, PCIe 6.0 achieves its 64-GT/s data rate, double that of PCIe 5.0, by moving from non-return-to-zero (NRZ) signaling to four-level pulse-amplitude-modulation (PAM4) signaling. Consequently, PCIe 6.0 requires some new test methodologies and patterns, including a new PAM4 Compliance Pattern that finds use in multiple measurements.

Figure 1. The new PCIe 6.0 Compliance Pattern signal. Click any image to enlarge.

The new Compliance Pattern is used for calculating signal to noise and distortion ratio (SNDR), as well as ps21TX (the package insertion loss) and the transmitter ratio of level mismatch (RLM). In addition, it is used to measure transmitter equalization coefficients.