11 | Keysight | EZJIT Complete Jitter and Vertical Noise Analysis Software for Infiniium Oscilloscopes - Data Sheet

The problem

Common spectral algorithm for RJ

extraction over-reports RJ.

Why?

Any Aperiodic Bounded Uncorrelated Jitter

(ABUJ) on the signal is factored into RJ.

A common source of ABUJ is crosstalk

from adjacent signals.

How does this affect me?

First, the RJ measurement can be

inaccurate. Second, when measuring Total

Jitter (TJ) vs. BER, TJ can be dramatically

overestimated due to the RJ multiplier. For

example, TJ = DJ + 14*RJ

an unfairly negative report of the overall

jitter performance of your serial data link.

Figure 14. Jitter separation with artificially extreme crosstalk using spectral algorithm for RJ

extraction. Notice the discontinuity in the BER bathtub.

Accurate Random Jitter Separation using Spectral and Tail Fit Algorithms

Figure 15. Jitter separation with artificially extreme crosstalk using tail fit algorithm for RJ

extraction. Notice the good fit to the BER bathtub and dramatically lower RJ and TJ results.

The solution

EZJIT Complete provides two distinct

algorithms for RJ extraction to ensure you

achieve accurate measurements under all

signal conditions.

The Tail Fit algorithm accurately extracts

RJ, even in extreme ABUJ/crosstalk

environments, by fitting directly to the

tail of the RJ,PJ histogram.

Figures 14 and 15 contrast the

two algorithms in a contrived jitter

measurement with extreme crosstalk.

You can see the tail fit algorithm in Figure

5 provides a much better fit to the BER

bathtub curve in the upper left and reports

significantly lower RJ and TJ.