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Re: [802.3_100GCU] Suggested return loss Vs. test fixture



I have seen presentations from connector vendors showing acceptable results with de-embedded in other venues. Its seemed to me to offer a more agonistic method to compare parts. Perhaps some these folks could share.

 

… Richard Mellitz,

Intel Corporation

 

From: Liav Ben Artsi [mailto:liav@xxxxxxxxxxx]
Sent: Thursday, July 19, 2012 3:04 AM
To: STDS-802-3-100GCU@xxxxxxxxxxxxxxxxx
Subject: [802.3_100GCU] Suggested return loss Vs. test fixure

 

Hi colleagues,

 

I could not sleep because of too many thoughts about the Tx/Rx return loss (and the jet-lag does not help either J).

 

I took the suggested return loss of comments 85/86 and put them against the possible test fixtures I have provided in former E-mails (please see picture) below.

I will be suggesting to keep the return loss as TBD for now and build up a consensus suggestion towards Geneva.

The current remedy for comments 85/86 (the way I see it) is suggesting no de-embedding of the test fixture, but is not aligned with test fixture reflections.

 

Therefore I suggest building up a consensus regarding the following issues:

1.       Measurement methodology (do we de-embed the test fixture from return loss measurements or not) – De-embedding accuracy and capabilities presentation would be very helpful here in convincing to go one way or the other.

2.       Provide a consensus return loss equation taking into account the decision of point #1.

 

Please see below the current suggested Tx/Rx return loss (Comment 86/85) (hoping I got it right).

Yellow – note 85/86 equation

Green - -12dB test fixture return loss

Orange – Via with a 4mil stub connected to a u-via

Grey – Short via è trace è another short via – both have 15mil stub

 

One can see that both extracted test fixtures are already quite close to the suggested remedy for Tx/Rx return loss (and this takes into account an ideal return loss package – this is just the test fixture return loss…).

 

Best regards,

Liav