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?

Testing Challenges in Motor Drive Systems (Part II)

Figure 1: This image depicts the complete design and
debug challenge posed by a variable-frequency motor drive

In our first post on motor drive systems, we broke down the major subsystems in a "generic" variable frequency drive (VFD) and discussed some of the test requirements in those subsystems (Figure 1). Next, let's have a look at some of the variations in real-world VFDs in terms of architectures and topologies.

Testing Challenges in Motor Drive Systems

Figure 1: The power section of a motor drive system requires
measurements of line input, PWM output, and efficiencies

Motors are everywhere in our world, and nowhere more so than in  our vehicles. For example, when's the last time you had to crank a car window up and down to pay a highway toll? Or, for that matter, when did you last manually adjust the seat position or rear-view mirror angles? These aspects of vehicles are all typically motorized these days.

The History of Jitter (Part III)

Figure 1: Latching a signal at the outermost of the blue

hash marks results in a BER of 10^-3, while latching it

at the innermost hash marks yields a BER of 10^-12

If you've been keeping track of our history of jitter, we left off in Part II in the late 1990s, by which time bit-error rates (BER) had become a predominant statistic for quantifying jitter. That was subsequently refined into thinking in terms of BER as a function of jitter.

Oscilloscope Basics: Choosing an Oscilloscope

Figure 1: An oscilloscope such as
Teledyne LeCroy's HDO6054-MS
serves a very broad range of
applications

Choosing an oscilloscope might seem to be a challenging task, but it doesn't have to be. Rather, it's a more-or-less logical process based on your measurement needs. Having said that, if the application for the instrument is "general lab work," the decision can become trickier.