Hi Jun,
Just a reminder that the original purpose of 8b10b is to achieve DC balance
(after an isolation Cap),
by not allowing too many consecutive 0s or 1s. This helps a receiver (Rx)
maintain the proper DC level
at its analog front end.
Regards
Samie Samaan
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On ;
Behalf Of jun zhang
Sent: Wednesday, January 06, 2016 5:33 PM
To: Cotton, Chris; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Influence of 8b10 encoder to eye diagram
Hi experts,
I have also collabrated with Keysight experts on 8b10b simulation. Using
Keysight IBIS Tx and Rx general models, we still find that no improvement when
we add 8b10b coding. Also I compare the periodic pattern with "0000000001" and
"01" and still not find the latter pattern will obtain more eye height than the
former one.
I doubt whether the benifit of 8b10b can improve SI performance.
Hope to your discussion
On Thu, Dec 31, 2015 at 9:31 AM, jun zhang <zhangjun5960@xxxxxxxxx> wrote:
Hi Cotton,
I simulate 1000,000 bits.
The PRBS is maximal length LFSR and register length is 11.
Regards
On Wed, Dec 30, 2015 at 11:34 PM, Cotton, Chris
<Chris.Cotton@xxxxxxxxxxx>
wrote:
Jun
8B10B tends to limit the length of consecutive identical digits and
hence tends to lower ISI which often times should help improve the
eye. How many bits are you simulating? What PRBS are you using? If
8B10B is making it worse among the first thing that I would look at
is to compare the bit pattern coming down the line in the non-8B10B case.
My guess is that this has nothing to do with needing a de-encoder
function in RX model.
Chris
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Aubrey Sparkman
Sent: Wednesday, December 30, 2015 10:07 AM
To: zhangjun5960@xxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Influence of 8b10 encoder to eye diagram
Ask your model supplier if their AMI algorithm works well with 8b10b.
Some do not and your results will look worse.
Aubrey
Sent from my iPhone
On Dec 30, 2015, at 7:52 AM, jun zhang <zhangjun5960@xxxxxxxxx> wrote:------------------------------------------------------------------
Hi experts,
In simulation of SAS-3 12Gbps by IBIS-AMI model obtained from
vendors, I accidently compare the eye diagram when TX with 8b10b
encoder and without 8b10b encoder and find that with 8b10b encoder,
both the eye heights and widths become worse than without 8b10b encoder.
Do you also approach such a phemomena and how can we explain it?
--
best wishes,
Jun Zhang
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best wishes,
Jun Zhang
