For Good Measure

RSS

Probing signals with a bandwidth below 100 MHz and voltage sensitivity above 100 mV is a no-brainer. Regardless of the type of signal or the source impedance, the venerable 10x passive probe is the answer. However, at bandwidths >100 MHz and with voltage sensitivity <100 mV, the 10x passive probe may not be the best option. In this article, SIJ technical editor Eric Bogatin introduces an easy-to-implement, low-cost alternative to the 10x passive probe specifically for power-rail measurements.

Verifying the modulation profile of SSC has historically been challenging because it involves a frequency shift as a function of time. Mike Hertz explains that by tracking the frequency measurement parameter, an oscilloscope can display the SSC modulation profile as a function of frequency versus time. Read on to see how it’s done.

Designers pushing the limits in their application can run into situations where the XO performance is inadequate for their next design due to the way it reacts to the noise and ripple in the power supply. To achieve optimal performance, they most likely will find they will need to do more than a simple datasheet evaluation to select their next XO. Read on for details on a PSNR test method to help select an optimal XO.

We searched for a superior cable for PDN measurements, then decided to create our own. Here’s the story.

Understanding how to make and interpret power supply impedance is very useful for optimized, low noise power supply design. With a simple pair of homemade probes, it’s easy to make the measurements using a compact VNA. Read on to find out how.

Obtaining accurate measurement data requires either accurate knowledge and accounting for the probe and fixture influence OR calibration methodology to remove these effects prior to measurement.

A TDR (time domain reflectometer) is an instrument that probably has the fastest rise time of any instrument in your lab, but how accurate is it? Eric tests accuracy using a DC Ohmmeter in this piece.

I received a demo version of a new quick and easy TDR. I decided to take it for a test drive by measuring all the cables I had lying around my lab. The results were surprising!

For this project, we will use an Atmel 328 microcontroller demo board, prepared with firmware to control it explicitly for our purposes, and with coaxial cables connected between the I/O pins and the input to the active probes of the scope. This interconnect provides a high bandwidth transmission line path for the signals.

If the die's I/O power rails are shared by the core power rails, here's a way to get your core power-rail measurements anyway.