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Re: [BP] Interference tolerance test channels



Title:
All,
I have not looked at the new files from Rich, but I have pulled in the files from Charles and I guess I don't understand what we are trying to accomplish.

The models Charles has sent are above the limit by a few dB in the lower freq areas, as others have already stated.  if you are looking for a real channel model, I have a few that fit close to this based on tests we did a few years ago ... models and data rejected by the group as not being real.  Even though they came from a real board.

I think what is bothering me most is that it appears you are all looking for that magic point where a designer crosses it and things go 'poof'.  The channel equation, and the equation set it comes from is developed from a complex set of data that covers many aspects.  Trying to eliminate design practise from it is very difficult to do and time consuming.  The 'poof' point is very much dependent on both the material choices and the design principles chosen.

For example, if I used 5mil geometry, standard pads, no back drill, power on the upper layers to reduce reflections, and no 'harsh features, my glass choices will show effects quite clearly.  If you thin out the geometry below about 4.75mils, registration and skin effect begin to vary such that material impact is hard to address ... with the major concern being reliability over 100s of back planes per month ... wider features are more reliable across manufacturing processes.

That said ... if you are trying to find a channel that sits right on the limit line, I can make a real one ... you just have to ask as a group.  My first thoughts then are .... do you want it on the current line or the one from two years ago?  Does it need to be available to everyone to measure or implement themselves?

-joel

Mellitz, Richard wrote:
Message

Oops… missed one.

Sorry,L

Rich

 


From: Healey, Adam B (Adam) [mailto:ahealey@AGERE.COM]
Sent: Wednesday, January 18, 2006 4:48 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Interference tolerance test channels

 

Rich,

 

Please be advised that your presentation title page contains a confidentiality disclaimer.  I will disable access to this file via the reflector archive.  I would recommend that you re-post an appropriately scrubbed version.

 

Thank you,

-Adam

 

-----Original Message-----
From: Mellitz, Richard [mailto:richard.mellitz@INTEL.COM]
Sent: Wednesday, January 18, 2006 4:09 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Interference tolerance test channels

Did it!  I built a channel that has 3db less loss at 5GHz with out impacting the loss at 1GHz. Also I created the AF coefficients to match this channel. See attached zip file.  I also checked the causality of the s4p as well. J

…Rich


From: DAmbrosia, John F [mailto:john.dambrosia@TYCOELECTRONICS.COM]
Sent: Monday, January 16, 2006 3:31 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Interference tolerance test channels

 

Steve,

But also realize that the general line also has built in margin for it to account for temperature, environmental, and  material variation as well.  The line as currently proposed has to be examined to look at from several aspects.  For example, the Molex channels are hugging the new proposed 23 dB line.  5” are on the daughtercard and 35” are on the backplane, which uses a typical 7 mil line.  So we are saying that to meet the skin effect at the lower frequencies we need a 7 mil wide line?  I think that is too far.  Look at the attached figure – 7 mil wide traces hug that line.  I think we have moved it too far upward.

 

I don’t see any efforts yet on reducing the problem via the crosstalk aspect of the problem.  Has that been abandoned?  I don’t think all of the burden at this time should be shifted to the channel, but should also be shared with the total allowable crosstalk.  Many of the channels did have margin.  We should look to striking a balance between the two.

 

John

 

-----Original Message-----
From: Steve Anderson [mailto:steve.anderson@xilinx.com]
Sent: Monday, January 16, 2006 2:52 PM
To: DAmbrosia, John F; STDS-802-3-BLADE@listserv.ieee.org
Subject: RE: [BP] Interference tolerance test channels

 

 

            John, all:

 

            But does a line made with the squared and cubed terms create a physically realizable channel?

 

            In the real channel I think there may be only two variables to play with:  skin effect and dielectric

absorption.  If we base simulations on something other than this, then I think bad things can happen like

non-causal effects.

 

            Steve A.

 

 


From: DAmbrosia, John F [mailto:john.dambrosia@tycoelectronics.com]
Sent: Monday, January 16, 2006 1:34 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Interference tolerance test channels

 

Guys,

Goergen asked the magic question.  Is it possible?  Yes it is.  We have a squared and cubed term to play with.  I am hoping Joel has some suggestions as well.  I just had a chance to do a quick scan and saw this.  I will be working on this stuff tonight

 

John

 

-----Original Message-----
From: Oganessyan, Gourgen [mailto:Gourgen.Oganessyan@MOLEX.COM]
Sent: Monday, January 16, 2006 2:24 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Interference tolerance test channels

 

Rich,

 

I see now what you refer too. I am not sure how you physically relaize a channel you are suggesting, keep low freq the same and come up at 5 GHz? Any physical channel should result in a tilted line?

 

Gourgen

 

-----Original Message-----
From: Mellitz, Richard [mailto:richard.mellitz@INTEL.COM]
Sent: Monday, January 16, 2006 1:05 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Interference tolerance test channels

 

 

The line didn’t only tilt. It also shifted. John D looked at a few channels as I attached. If we shift, it’s got an impact for KX and KX4.

…Rich

 

 

 


From: Joe M Abler [mailto:abler@US.IBM.COM]
Sent: Monday, January 16, 2006 1:15 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Interference tolerance test channels

 


The new channel appears to be inline with what we stated - a tilt of the line from DC to about a 3dB drop at 5GHz.  Why do you feel the lower frequencies need to stay fixed?


Thanks,        Joe


Joe Abler                                                             abler@us.ibm.com
IBM Systems & Technology Group            919-254-0573
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"Mellitz, Richard" <richard.mellitz@INTEL.COM>

01/16/2006 10:41 AM
Please respond to "Mellitz, Richard"

       
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        Subject:        Re: [BP] Interference tolerance test channels




Hi Charles,
DC and low freq's went down way to much! Can you create a model with the
same losses at say 1GHz or so and 2 dB less at 5GHz? I thought that's
what we agreed.
... Rich

-----Original Message-----
From: Charles Moore [mailto:charles.moore@avagotech.com]
Sent: Friday, January 13, 2006 8:42 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: [BP] Interference tolerance test channels

guys,

    I propose that we use the model ITTC_23.s4p for reduced attenuation
EIT modeling.  If it really will not work, ITTC_20.s4p is available as a
bail out channel.  If it looks too easy, let me know and i will step it
up just
a tad.

    The numbers refer to the fitted attenuation at 5.15...GHz.

                                 charles

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