Rogue waves can ruin your power
With today's high-speed digital circuits making demands on PDNs (power distribution networks), impedance in power and return planes can create losses that result in bit errors. That impedance combines with capacitance to create resonant frequencies in a PDN. If signal hits those resonant frequencies, it can produce unwanted signals called "rogue waves."
The video below shows the natural and forced time-domain responses resulting from an impedance peak within a PDN. A PDN impedance with multiple peaks can result in much larger voltage excursions if a specific load current pattern is generated. The determination of this specific load current pattern isn't always easy to find. From the video, you'll learn:
- How are the natural and forced responses different?
- How many cycles are required to achieve the maximum amplitude response.
- Why target impedance is a valuable tool in PDN design, but requires the PDN impedance to be relatively flat to work.
- How optimizer simulation can easily determine the load pattern required to generate the largest rogue wave.
- To recognize the PDN impedance characteristics that are predictors of the potential for a rogue wave.
PDNs containing a single impedance peak and three impedance peaks are simulated in order to show the responses. A simulator optimizer is used to determine the load current stimulus pattern to achieve the maximum voltage excursion. The potential for a rogue wave is evident from a few particular characteristics of the PDN impedance.
Click here to download the simulation files used in the video.