Data Decoding at 10 Gbit/s

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- Martin Schimmelpfennig
  
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vor 18 Jahren

Wed, Dec 21, 2005 12:23 PM

Hi,

Gbit/s per channel. For transmission a standard 8B/10B is to be applied. My concern is now how to achieve real-time decoding of the 8B/10B transmission code at 10 Gbit/s with that technology? Can that easily be achieved? What is state-of-the-art? As far as I know the 8B/10B decoding cannot be down by a simple lookup table because the corresponding code words depend on the running disparity of the previous transmitted data and there is no simple

1-on-1 mapping. Since the 8B/10B coding is a self-synchronizing (?) code (i.e. the clock can be retrieved from the transmitted data) I would have to use a kind of clock recovery at my SERDES input. Another question would be if a PLL at the input is advisable or even feasible at data rates of 10 Gbit/s.

I would be very thankful if some of you could give me a hint.

Best Regards

Martin

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- MaWin
  
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gepostetes
vor 18 Jahren

Wed, Dec 21, 2005 4:02 PM

"Martin Schimmelpfennig" schrieb im Newsbeitrag news:dobhcn$kpq$ snipped-for-privacy@mamenchi.zrz.TU-Berlin.DE...

Is it possible to use only one newsgroup instead of a crosspost without followup to 7 ?

Really ? 10Gbit/channel? I know only of 3.2GBit technologoy, who's manufacturing the 10GBit device ?

Google for "8B/10B" and read the first hit from the Siemens Communication Lexicon and you understand that at least workers of Siemens Communication Group do not have the slighest clue about 8B/10B, but THINK that they know everything.

State machine, depending on your output (8 bit parallel ?) clocking in single bits and decode using minimized terms (PLA) instead of table ROM.

Only PLL, clock of chip must be derived from clock of input.

Synchronizing (digial) is not used for bit clock signal, but for word clock.

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- Falk Brunner
  
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gepostetes
vor 18 Jahren

Wed, Dec 21, 2005 5:59 PM

MaWin schrieb:

Indeed!

Vitesse, TDK etc.

At 10 Gbit/s you dont want to use 8B10B, since it wastes 20% of bandwidth for coding overhead. Most (all?) 10G systems use 64B/66B instead. Uses only 3% overhead.

Sure. But even 8bit is a little bit too fast (1.2 GHz). BEtter go for 16 oder more bit, this get your clock rate down to feasable levels. The price for slower clocks is silicon area.

???? You just need one (maybe even two, RX and TX)

Have a look at the VSC8476 from vitesse, this might give you an idea what you are trying to do.

Regards Falk