Fierce Electronics Editor Matt Hamblen interviewed Michael Schnecker of Rohde & Schwarz at the News Desk at Sensors Converge 2022.
When asked “What do you need more than the most basic scope to analyze direct current?” Michael replied, “That question is quite common, because DC is not that challenging. It does not move very much but the reality is that power rails these days are pretty low voltage and that you need to look at very small noise on those rails, so the noise on the scope itself is really important. Folks these days might buy an expensive scope but that might be a little too noisy for the application. The scope doesn’t necessarily have to be inexpensive, but you definitely want one with low noise which are available at different price points.”
When asked “What are the challenges that require higher performance scopes?” Michael stated that “The first biggest challenge was the small ripple voltage and trying to understand how precisely large it is, which can range from tens of millivolts. The real challenge would be getting the right kind of probe, since the basic probe that comes with the scope is sometimes not adequate.” Michael circled back to low noise probes as they have a lower attenuation factor; instead of ten to one, look for a one to one probe.
When asked “Is there a particular measurement capability that is not typically considered by engineering types?” Michael answered, “I like to answer questions like that because people think about bandwidth sample rate, but what a lot of folks don’t think about is the refresh rate of the scope. How fast the Oscilloscope can acquire a wave form and measure that wave form. The reason being that if someone is trying to find the worst case range of voltage, the more times you can accurately measure that, then you will find the range more accurately, the peak to peak value. The speed of throughput is really important, because you could run a set test for 10 seconds and maybe get all the information you need on a fast scope, but on a slower one it might take minutes to hours to get where you want to be. If you run a test for over an hour, you are really not running a test anymore. Speed throughput is something that people probably don’t think too much about.”