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DS560MB410: max boost clarification

Ty Johnson
Prodigy 20 points
Part Number: DS560MB410
Other Parts Discussed in Thread: DS280DF810, DS560DF410, DS280MB810, DS110DF111, DS110DF410

I have a very limited understanding of redrivers and retimers so some application assistance would be most appreciated. For my application I am using 10Gbps fibre and would like to get a boost at 5ghz of around 30dB per channel.  I am considering the DS560MB410 because we may increase the speeds in the future so having the ability to go up to 28Gbps is apealing.

  1. From the data sheet it looks as though max gain for DS560MB410 at 5ghz is around 12dB per channel. Is that correct?
  2. Do you have any suggestions if I were to go with a retimer instead? I am thinking of the DS280DF810 part but I noticed the max boost was around 14dB

 

Any help would be much appreciated.

Thank you!

  • +1
    TI__Mastermind 20782 points

    Hi Ty,

    Thanks for the background on your investigation.  I have a couple questions that come to mind.

    1) Do you have a particular channel requirement?  Is there any reason you're considering a 4 channel redriver and 8 channel retimer?  Depending on your requirements, other devices that might be worth looking at are DS280MB810 and DS560DF410.

    2) You mention that in the future you might increase speeds up to 28 Gbps.  Would this be on a different platform?  If you already have 30 dB of loss at 5 GHz, I think your loss at 14 GHz would be beyond what a single redriver/retimer could equalize.

    3) For 10 Gbps fibre, is this a front port application, like XFI/SFI?  Is there any block diagram you might be able to share?

    Regarding your questions:

    Ty Johnson said:
    From the data sheet it looks as though max gain for DS560MB410 at 5ghz is around 12dB per channel. Is that correct?

    1) Your understanding is correct, but one thing I'd like to note is that this figure was taken from the cable equalization table.  Depending on whether you're equalizing cable or PCB, you might observe better performance from using the CTLE in PCB mode.  So I'd say a max of 9-12 dB at 5 GHz with DS560MB410.

    Ty Johnson said:
    Do you have any suggestions if I were to go with a retimer instead? I am thinking of the DS280DF810 part but I noticed the max boost was around 14dB

    2) Could you clarify where you saw max boost of 14 dB?  At 14 GHz, we expect 30+ dB of equalization.  I have an internal simulation of the CTLE curve at the max boost that indicates closer to 16-18 dB at 5 GHz, although 14 dB might be a good conservative estimate.

    If you need to equalize 30 dB of loss at 5 GHz, I think you should also consider our 10G redriver/retimer parts.  I understand that these will have to be replaced on a 28G platform, but since our 28G/56G devices have max equalization of around 30 dB at 14 GHz, they will have less equalization at 5 GHz than our 10G parts.  Depending on channel requirements, DS110DF111 or DS110DF410 could be good options.

    Thanks,

    Drew