Re: [BP] ATTN: Magesh - Broadcom simulation results
Joe,
We may have interpreted the draft differently or we differ in
translating DCD's contribution to DJ.
Based on discussion at the Jan 2006 meeting and the presentation
http://www.ieee802.org/3/ap/public/feb06/anderson_01_0206.pdf,
we want to limit the clock period variation in alternate cycles to
within +/-2.5% or 0.05UIpp
In my simulations, the transmitter is modeled with "odd" clock periods
2.5% longer than
ideal and "even" clock cycles 2.5% shorter. When you plot these
waveforms with respect
to an ideal clock reference, the inner eye opening is 0.975UI. The
transition width
is 0.025UI. The eye closure or DJ component is 0.025UIpp.
From the definition of DCD in the draft, this transmitter has DCD =
0.05UIpp.
"The Duty Cycle Distortion is defined as the unsigned ratio of the
difference in the mean pulse
width of a "1" pulse compared to the mean pulse width of a "0" pulse (as
measured at the mean of the high
and low voltage levels in a clock-like repeating 0,1,0,1 bit sequence)
and the nominal pulse width."
Regards,
Magesh
________________________________
From: Joe M Abler [mailto:abler@us.ibm.com]
Sent: Monday, May 08, 2006 5:16 PM
To: Magesh Valliappan
Cc: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] ATTN: Magesh - Broadcom simulation results
Thanks Magesh. Could you clarify what amount of DCD you're
applying for the xtlk BER results? Your table indications "DCD =
0.05UIpp (eye closure = 0.025UIpp)". Which is it? The spec calls for
up to 0.05UIpp closure. Based on the following line where you state "DJ
at package output, excluding DCD = 0.105UIpp" and that your TJ =
0.28UIpp and RJ = 0.15UIpp it would appear that the amount of DCD you're
applying is 0.025UIpp. That by the way is half what I apply, which
would essentially explain why you're not seeing the same level of impact
I am.
Thanks, Joe
Joe Abler
abler@us.ibm.com
IBM Systems & Technology Group 919-254-0573
High Speed Serial Link Solutions 919-254-9616
(fax)
3039 Cornwallis Road
Research Triangle Park, NC 27709
Magesh Valliappan <mageshv@BROADCOM.COM>
05/08/2006 01:48 PM
Please respond to Magesh Valliappan
To: STDS-802-3-BLADE@listserv.ieee.org
cc:
Subject: Re: [BP] ATTN: Magesh - Broadcom
simulation results
I have updated the presentations with clarifications on
simulation conditions and attached them to this email.
The transmitter conditions in both are based on the latest
version of the 802.3ap draft and Charles' email
regarding EIT simulations. The receiver conditions are similar
to what I have presented at the last meeting.
Magesh
________________________________
From: Joe M Abler [mailto:abler@US.IBM.COM]
Sent: Friday, May 05, 2006 5:52 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: [BP] ATTN: Magesh - Broadcom simulation results
Hi Magesh,
I'm trying to compare some of your simulation results with mine
but can't get too far because I don't have sufficient information on
your simulation conditions. You put some very basic information in your
presentations such as launch voltage and rise time, but I'd appreciate
it if you could provide additional information on your assumptions for
jitter (Tx & Rx breakdown including DCD), termination values, clock
offset, data pattern type, random noise level, any accounting for CDR
algorithm, etc. I'm currently looking at your last presentation
villiappan_c2_0506 and would appreciate if you could send me the
conditions for those results. More generally though, I'd like to
recommend that you update your other presentations with such
information and perhaps ask Adam to repost them. Anyone trying to
reference these in the future really wouldn't get full benefit fro! m
them without knowing the conditions behind them.nt>
Thanks, Joe
Joe Abler
abler@us.ibm.com
IBM Systems & Technology Group 919-254-0573
High Speed Serial Link Solutions 919-254-9616
(fax)
3039 Cornwallis Road
Research Triangle Park, NC 27709
#### kr_xtlk_ber.pdf has been removed from this note on May 08,
2006 by Joe M Abler
#### eit_sim_results.pdf has been removed from this note on May
08, 2006 by Joe M Abler