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SATA Return Loss measurements: De-embedding the adapter?

Question asked by DerekM on Sep 11, 2007
Hi, first post, I hope it's in the right area!

Recently we carried out the SATA TXRX tests (impedance and return loss measurements), using the 86100C DCA-J, option 202, and the 54754A TDR module. While the results were good, we did notice a difference depending on the SMA-to-SATA adapter used to connect between the DCA-J output cables and the test board. For example, the Crescent Heart Test Fixture yielded result which differed by up to 5dBs compared to results obtained by a lower quality, custom-built, adapter. Ideally we would like to de-embed the adapter from the measurements, but are unsure of the best method to approach the problem. So, some questions:

1. Can the test equipment listed above be used for the de-embedding process? Do we need two 54754 TDR modules? Is there any software available for this test system which can be used to directly carry out the process?

2. From a theoretical viewpoint, what is the best way to approach the problem? Revision 2.6 of the SATA spec details an equation based on the attenuation loss, input reflection, etc, of the adapter (p248 in SATA 2.6, dated 15-02-07). Is this based on the 12-Term Error Model used in other network analyzer applications? Or is there another mathematical approach I need to look at?

3. Has anybody any web links to some decent information on the process? I've searched long and hard and struggled to find anything worthwhile.