Stumbles in signal processing: Oscilloscope frequency response

As electrical engineers move towards digital circuits with increasingly short rise-times, it is sometimes useful to remember that our test equipment is not always able to properly represent a signal. Knowing what is going on with your signal and test equipment at a basic level might prevent you from making incorrect assumptions during your next project.

Oscilloscopes display potential differences that are measured in the time-domain. Analog to digital converters track and display the potential difference between the probe tip and the ground return over some period of time. The time-domain signal is presented on the screen to a viewer, but oscilloscopes have signal chain limitations in the frequency-domain. Since frequency limitations can alter a waveform’s appearance in the time-domain, it is worth understanding a bit more about the frequency limitations of your oscilloscope and how they can affect the time-domain signal you see. If you are tracking signals near the upper limitations of your test equipment’s frequency response, there is an excellent chance that you are seeing a modified version of your board’s signal.

To learn a bit more, check out this video. Enjoy!

As a note, this video is a quick overview of a larger topic. If you want to go more in depth or prefer to read about this topic, check out the white paper.