You need to test, we're here to help.

You need to test, we're here to help.

19 May 2015

The History of Jitter (Part IV)

An example of a time-interval error track
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?

07 May 2015

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?

15 April 2015

Testing Challenges in Motor Drive Systems (Part II)

Yhe complete design and debug challenge posed by a variable-frequency motor drive
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.

07 April 2015

Testing Challenges in Motor Drive Systems

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

02 April 2015

The History of Jitter (Part III)

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
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.

27 March 2015

Back to Basics: Choosing an Oscilloscope

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

20 March 2015

Using Histograms (Part III)

A simplified view of a push-pull amplifier showing the source of crossover distortion
Figure 1: A simplified view of a push-pull amplifier
showing the source of crossover distortion
In this third post in a series on using an oscilloscope's histogram capabilities, let's take a look at using histograms as a diagnostic tool. Diagnosing problems in a circuit calls for good skills and some intuition on top of good measurement tool. In general, though, the more ways in which you're able to look at a problem, the more likely it is that you'll turn up the root cause.