The History of Jitter (Part V)

Figure 1: Applying PLLs for clock-data recovery is not
unlike tapping your feet to the beat of music

A milestone in the history of jitter measurement came in the 1990s with receivers that could reveal the slowly varying component of jitter that became evident in time-interval error (TIE) tracks. That led to the advent of using phase-locked loops (PLLs) for clock-data recovery. In turn, PLLs opened new horizons in jitter analysis.

The History of Jitter (Part IV)

Figure 1: An example of a time-interval error track

In the previous installment in this series on the history of jitter, we'd reached the cusp of the new millennium. The in-vogue methodology for jitter analysis of the day was using edge crossing-point data in the form of a histogram and fitting Gaussian functions to the tails of the plot. But tail fitting, as we well know, isn't for the faint of heart. How would test methodologies move forward to surmount that hurdle?

Using Histograms (Part IV)

Figure 1: A histogram of delay between traces C1 and C2

with an unknown event occuring 2.5 ns outside of

expected range

In previous posts on the topic of histograms, we've considered examples of how looking at signals in the statistical domain in addition to the time and frequency domains can be a great aid in pinning down the root cause of problems. But what about going in the other direction? Suppose you spot something unusual in a histogram and want to examine the waveform?