[SI-LIST] Re: Digital F-mux
- From: steve weir <weirsi@xxxxxxxxxx>
- To: David Palmer <dpalmer@xxxxxxxxxxxxx>
- Date: Tue, 08 Feb 2011 16:13:13 -0800
David, you will still have to deal with the extra parasitics of the
trace to and the resistor mounting pad structure on the channel side at
both ends of the link. In silicon that can be made very small. On a
PCB it is going to be a lot harder to make that transparent. At low bit
rates this is not an issue. If you are above 3Gbps and you don't have a
lot of margin you are setting yourself up for a lot of time getting
intimate with your 3D field solver. I would look exhaustively for a
digital solution first.
Steve.
David Palmer wrote:
> 4K resistor.
> The OOB operates in absence of link unfortunately.
>
>
> steve weir wrote:
>
>> David, the multiplexing isn't the hard part. The hard part is finding a
>> way to separate the two signal bands without creating a discontinuity in
>> the channel impedance. If you can make your own silicon it seems that
>> could be done. I don't have any good suggestions on how to do that with
>> any existing FPGA at appreciable line rates.
>>
>> I think that your life will work out much better if you steal a small
>> amount of bandwidth higher up in the protocol stack than if you try to
>> get tricky with the physical layer.
>>
>> Steve.
>>
>>
>> David Palmer wrote:
>>
>>> Has anybody here ever attempted to multiplex very low edge rate OOB
>>> signals onto a doubly-AC-coupled high speed serial link to save on
>>> cable conductors? Did you get fired?
>>>
>>>
>>>
>>
>
>
--
Steve Weir
IPBLOX, LLC
150 N. Center St. #211
Reno, NV 89501
www.ipblox.com
(775) 299-4236 Business
(866) 675-4630 Toll-free
(707) 780-1951 Fax
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