If your device fails a test, you need to

determine how it failed. To use the PCI

Express electrical test software, you must

install Keysight’s high-speed serial data

analysis software, which provides you with

several powerful debugging tools. The

8b/10b decoding feature lets you identify

data-dependent errors that result in eye

mask violations caused by inter-symbol

interference (ISI). You can perform 8b/10b

decoding to capture and display serial

data synchronized with the analog view of

a serial data stream (For PCIe 1.x and 2.x).

Powerful Debugging Aids

Figure 24. The 8b/10b decoded symbol information is shown below the appropriate portion of a PCI

Express signal using the E2688A software.

Use the 10-bit code display to validate

your compliance pattern conforms to

the PCI Express standard

Make sure your compliance pattern has

the proper disparity (K28.5-, D21.5,

K28.5+, D10.2)

Using the E2688A Serial Data Analysis tool

you can test for illegal characters in your

compliance pattern. You can also use the

mask test feature to identify the specific

digital patterns that caused a specific

failure in the eye diagram when testing

under the 1.1 specification (using a first

order PLL).

For 2.0 testing you can use a first or

second order PLL for clock recovery and

apply a TIE brick wall filter (included with

the E2688A Series Data Analysis package)

to achieve a proper clock filtering.

Figure 25. Check for illegal characters in the compliance pattern (such as SKP’s) using the E2688A

Serial Data Analysis tool.

Problems with early silicon still persist with new PCI

Express devices. Make sure yours isn’t one of them. SKP

characters are not allowed in the compliance pattern.