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I am having trouble finding an Ethernet PHY that specifically advertises as being compliant with 1000Base-KX (to be sent over a VXP backplane, a single RX pair and a single TX pair).

I found a comment here: Connecting two Ethernet PHY without magnetics?

That says you can put most modern PHYs into a 1000BASE-KX mode by doing some configuration bit tweaks. Can anybody elaborate on which bits would need to be changed, and how? Is this using a standard 1000BASE-T PHY?

Sittin Hawk
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1 Answers1

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No relation with 1000BASE-T.

It's the 1000BASE-X encoding, found in optical fibre links 1000BASE-SX and 1000BASE-LX, but used in backplanes.

There is also 1000BASE-CX for short links over special cables.

It's described in the 802.3 standard (freely downloadable)

Optical interfaces are often connected through removable SFP adapters, the signals that drive these modules are quite similar to 1000BASE-KX. Some Ethernet PHYs supporting optical links are compatible with -KX.

TEMLIB
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  • "Some Ethernet PHYs supporting optical links are compatible with -KX." Could you provide an example part? – Sittin Hawk Mar 10 '21 at 21:03
  • google `1000base-kx spf` – jsotola Mar 10 '21 at 22:49
  • I did. I'm not finding an obvious solution. SFP modules typically have standard connectors (fiber or RJ45), so I'm not sure how that would help get to an electrical backplane. Do you have a cable attached to an SFP module and then connect that into a PCB connector that has traces going to the backplane? – Sittin Hawk Mar 11 '21 at 18:00
  • So I found some PHYs that support 1000BASE-X (Marvell 88E1512), with a diagram showing a SERDES/SGMII interface from the PHY connecting to a "Fiber Optics" block (1000BASE-X or SFP). If I put this PHY into a 1000BASE-X mode, what additional hardware would be needed to send this SERDES/SGMII signal to the backplane to be compliant with 1000BASE-KX? Do I connect it directly? – Sittin Hawk Mar 11 '21 at 19:14