The Right Materials for 40G

Your choice of board materials and connectors can have a significant impact on system performance, and in turn, 40G compliance. But how do these choices work in combination? At RadiSys, we’re evaluating these combinations so that you can see the effects of each choice you make.

FR4 Board Low-Loss Board
HM-Zd Connector Insertion loss, some crosstalk,
some reflections
Reflections from connectors
HM-Zd Plus Connector Insertion loss Good (less insertion loss, less crosstalk

With an FR4 board and an HM-Zd connector, we’re finding insertion loss, some crosstalk and some reflections – all in all, not a combination that can satisfy 40G requirements. If you exchange the FR4 board with a low-loss board, you’ll still get some reflections but no attenuation. In other words, it could be worse.

Now, let’s say we have an FR4 board with an HM-Zd Plus connector. Here we still have some insertion loss due to the board material, but we’re doing better.

Lastly, in a combination best suited for 40G, we have a low-loss board and an HM-Zd Plus connector. Now we’re good. We have significantly less insertion and crosstalk. Just as importantly, we have less overall risk.

What is right for your business? That’s depends on your unique requirements. Here at RadiSys, we’re here to help. We can help you weigh the risks, costs and benefits and assist you with understanding the choices you face and the trade-offs involved. We can also help get some discussion going.

Where are you on your roadmap to 40G?

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