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Hello Stefan, thanks for the material. I have a couple of comment that I hope can help out. Slide 4/9: If you want to de-embed I strongly suggest single-ended traces, which means the spacing between traces must be many times the dielectric thickness in the entire routing. I still do not recommend de-embedding
in general, and instead suggest using the results as-is with the jig. It makes it much simpler for the users and with good jigs it should not matter for the measurements that we want to do. “Low-impedance” connection to the GND plane or another PCB should be defined. It could be defined physically, such as using wide metal brackets and continuous connections between the PCBs and them as well as
to the metal GND plane. SMA – I suggest using 3.5mm connectors instead of SMA. I use Huber&Suhner air-dielectric 3.5mm connectors which I measured as much better than e.g. Johnson SMA which are routinely used for “miscellaneous” lab
measurements. I am not sure if these H&S connectors come in all shapes we might want to use, I use straight edge-mount type. Slide 5/9: Again, I envision a metal bracket (typically L-shaped) to provide connection to the metal GND plane. Slide 6/9: Again, I generally prefer taking data with the jig included, providing I can design and demonstrate that the effect of the jig does not alter the data in any significant way and we can live with it. De-embedding
should be done only on special occasions when absolutely needed. FR4 vs. Rogers – it depends on what you want to measure and how the jig is designed. FR4 might be used for some (but not balance) measurements. In general, to avoid confusion and issues that people who are not
so familiar with little but very significant details, I prefer specifying Rogers and keep it simple and on the safe side. One general comment on the test jigs shown in the photos is that they are designed to measure the connector only. While this is important to know the connector-only performance and it needs to be done, the performance
of the connector mounted on the cable is what really matters in the end. E.g. the un-twisted section of the wires, and their relation to the other wires in the vicinity are so critical that they can completely destroy an otherwise “good-looking” connector.
Therefore, in my very strong opinion, these jigs must include a section of the cable, perhaps something like 5-10 cm or so – as appropriate for each connector type under test – and the influences of various possible wire arrangements in that area should be
included in the measurement. I am sure this would show that even with the best connectors and cables in the world, this area can influence the overall performance drastically and prove to be the weakest segment of the link. Such a test setup would also allow
understanding any wire-management that might help improve it. I hope this helps. Neven From: Stefan Buntz [mailto:stefan.buntz@xxxxxxxxxxx]
Dear colleagues, attached you find a some additional notes on measurement adapter/test setup and a clarification of what – at last – I understood as “extended link segment”. Please don’t understand this slide as a finished proposal for a unified test setup – I would like to try to add more additional information to this slideset and summarize all the inputs we have (please give feedback if you have any additional input, most probably I didn’t get all comments during our F2F meeting)
before we go on an try to define the unified test setup/adapter. Regards, Stefan Von: Mehmet Tazebay [mailto:mtazebay@xxxxxxxxxxxx]
Dear Colleagues, Please find the attached meeting notes from our F2F meeting in Geneva. We look forward to working with you.
Best Regards, Mehmet Tazebay
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