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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