Why is Power Integrity Hot (or is it Cool)?

When designing next-generation products, the common theme is "faster, smaller, cheaper".  When that is combined with longer battery life and lower power consumption requirements, the design challenges can be daunting.  And one thing you know for sure, the project schedule is not going to be extended to allow you to overcome all these challenges.

It certainly makes sense that every electronic product designer has a tool that enables analysis of the power delivery network.  While components can tolerate certain fluctuations in power and ground rails, there are limits to that tolerance.  Having planes that are so heavily perforated that they look like Swiss cheese and scraping away at fill areas to make room for signal routing are only going to exasperate the voltage fluctuations.  But when you're under the pressures of "faster, smaller, cheaper", these are the compromises that need to be evaluated.

DC power analysis, also known as IR drop analysis, is commonly the first tool electronic product designers will turn to when facing these challenges.  However, one common complaint has been that the analysis is done at a static temperature.   With the current returning through perforated planes and choke areas (neck down areas) in the plane, the current density and, therefore, temperature, are going to be higher than in other portions of the PCB where these conditions do not exist. So, analyzing IR drop at a static ambient temperature can lead to inaccurate IR drop predictions. 

One solution might help is to use a tool (shown as below), where IR drop analysis is done concurrently with thermal analysis. This means the tool will predict the correct DC voltage drop based on the operating temperature of that region of the electronic product's PCB. 

In addition to electrical-thermal co-simulation, this tool is also capable of analyzing multi-board configurations. Which means products that have memory cards attached can have the full system power delivery network analyzed.

Here is an 11-minute demonstration video with additional details:

If you are using Allegro to design your PCB or IC package, you will have the benefit of accessing this electrical-thermal co-simulation tool  directly from the designer’s desktop.  Accurate IR drop analysis can be run in batch mode and the report file provides links that point the designer to exactly what parts of the design are out of spec.  This means you don't have to switch back and force between different tools, which gets you to a completed design much faster.

Feel free to leave comments below, we are open to all kinds of discussions.

(Tool demonstrated is  Sigrity™ PowerDC)

Team Sigrity