Why do I have to validate my board design?

For some of us this is a rhetorical question. Of course you will need to validate!! However, I’m surprised how much I am seeing this mindset in the marketplace.

ASSET has been providing validation tools for Intel Architecture (IA) based designs for the last six years. During this time, we have seen a significant increase in signal speeds that has created challenges to the signal integrity (SI) engineer. For example, moving to the Intel® QuickPath Interconnect (Intel QPI) bus changed the validation process. The maximum Intel QPI frequency on Nehalem is 3.2 GHz (6.4 GT/s). To put this in perspective, the maximum Front Side Bus frequency was 200 MHz. In one generation of IA based products, there was a 16x speed increase!

This increase in speed requires a new approach from designers. Read on…

The Impact of the Speed Change….

Let’s use the example of an airplane designer. Imagine an engineer designing traditional airplanes whose next project is a supersonic jet. Transitioning to supersonic speeds requires an entirely new mindset. It involves a new approach to propulsion systems, aerodynamics, and materials.

Impact of speed change

This is similar to the change to high frequency. Speeds greater than 1 GHz require special consideration.

There are no standard design rules. All designs are unique. Any design recommendations would provide a general starting point rather than a specific design rule. They may not allow enough design flexibility. Most importantly, any deviation would require simulation and validation.

Engineers must understand implications of design variables like materials, process, valuations over time, and others. These variables must be understood on how they affect cost and performance.

This is physics. Issues regarding material properties are due to signal speed and will affect ALL platforms with signal speeds of greater than 1 GHz to some extent, regardless of application. The severity of the effect will depend on the application. The industry has already started seeing this issue with PCI-Express on both Gen 1 and Gen 2, and in its 3rd generation is moving to 8 GT/s. These issues will only get worse as speeds keep rising.

Glenn Woppman