[SI-LIST] Re: Signal crossing Split plane
- From: steve weir <weirsi@xxxxxxxxxx>
- To: leeritchey@xxxxxxxxxxxxx
- Date: Wed, 21 Nov 2007 18:54:47 -0800
Yes, I do. Do you want to give it a go?
Best Regards,
Steve
Lee Ritchey wrote:
> Iv've got the test PCBs, do you have the tools?
>
> Lee
>
>
>
>> [Original Message]
>> From: steve weir <weirsi@xxxxxxxxxx>
>> To: <leeritchey@xxxxxxxxxxxxx>
>> Cc: Charles Harrington <ch_harrington@xxxxxxxxx>;
>>
> <shlepnev@xxxxxxxxxxxxx>; <scott@xxxxxxxxxxxxx>;
> <sunil_bharadwaz@xxxxxxxxx>; SI LIST <si-list@xxxxxxxxxxxxx>
>
>> Date: 11/20/2007 5:45:16 PM
>> Subject: [SI-LIST] Re: Signal crossing Split plane
>>
>> Lee I don't think the original problem would have warranted
>> measurements. But the thread has moved significantly since then. It
>> might be a fun test of Simbeor to model your test vehicle and compare
>> results. Rather than just drive with a TDR, it might be fun to drive
>> with a pulse generator that can be set to the simulated resonant
>> frequency and see if doing so impacts measured results in real life the
>> way simulation predicts.
>>
>> Best Regards,
>>
>>
>> Steve.
>> Lee Ritchey wrote:
>>
>>> I've watched this thread for a while now and haven't seen anyone suggest
>>> making measurements. I've done lots of that and have several test
>>>
> boards
>
>>> in my lab that represent the kind of plane splitting that is done to
>>> accommodate two Vdds in the same plane. I've run traces over these
>>>
> splits
>
>>> and measured them with a TDR with a rise time of 40 pSEC. There is no
>>> detectable disturbance of the signal when this is done. (Of course, the
>>> Vdd PDS designs need to be done such that the frequencies in the signals
>>> crossing the planes can be properly supported. If that has not been
>>>
> done,
>
>>> worrries about crossing plane splits will be the minor problem.)
>>>
>>> I've also measured hundreds of vias used to change layers from top to
>>> bottom of a PCB and from adjacent layer to adjacent layer. Again,
>>> measuring these vias with the same TDR they behave as though someone has
>>> attached a very small parasitic capacitor, on the order of .5 pF for a
>>>
> 12
>
>>> mil drill in a 100 mil thick PCB. There has been no detectable
>>>
> coupling of
>
>>> energy into the space between planes.
>>>
>>> Same thing for right angle bends. Not a detectable source of signal
>>> degradation or EMI.
>>>
>>> Sometimes a little lab time saves a lot of agony and speculation.
>>>
>>> If there are those out there who have tests that prove otherwise,
>>>
> perhaps
>
>>> they should publish the results. I've published mine several times as
>>>
> have
>
>>> others.
>>>
>>> Hope this helps those who are confused by all of the complex
>>>
> explanations
>
>>> that have been offered without any supporting measurements.
>>>
>>> Lee Ritchey
>>>
>>>
>>>
>>>
>>>> [Original Message]
>>>> From: Charles Harrington <ch_harrington@xxxxxxxxx>
>>>> To: <shlepnev@xxxxxxxxxxxxx>; <scott@xxxxxxxxxxxxx>
>>>> Cc: <sunil_bharadwaz@xxxxxxxxx>; SI LIST <si-list@xxxxxxxxxxxxx>
>>>> Date: 11/20/2007 2:45:54 PM
>>>> Subject: [SI-LIST] Re: Signal crossing Split plane
>>>>
>>>> Yuriy,
>>>> I agree with some of your views. However, they contradict your via
>>>>
>>>>
>>> models.
>>>
>>>
>>>> I couldn’t reply yesterday, because I was trying search for the
>>>>
>>>>
>>> reference I mentioned, since you needed it. Many other people replied
>>> off-line and so needed the reference. Got it from IEEE Xplore.
>>>
>>>
>>>>
>>>>
>>>> A Novel Methodology for Defining the Boundaries of Geometrical
>>>>
>>>>
>>> Discontinuities in Electronic Packages
>>>
>>>
>>>> Ndip, I.; Reichl, H.; Guttowski, S.;
>>>> Research in Microelectronics and Electronics 2006, Ph. D.
>>>> 12- 15 June 2006 Page(s):193 - 196
>>>>
>>>>
>>>> You mentioned in your mail that the near field zone as a result of
>>>>
> the
>
>>>>
>>>>
>>> higher-order modes excited at the via expands with frequency and is very
>>> small. I agree with you.
>>>
>>>
>>>> But the question is this. How small is it? How small or big is at 1
>>>>
>>>>
>>> GHz, 10 GHz, 20 GHz? Have you ever studied it? You have to take this
>>>
> zone
>
>>> into consideration when studying vias or any other structures that
>>>
> excite
>
>>> higher order modes.
>>>
>>>
>>>> The method proposed in this paper is quite illustrative and
>>>>
> useful. I
>
>>>>
>>>>
>>> understand it this way (Please correct me if I understand it wrongly):
>>>
>>>
>>>> These higher-order modes (e.g., TE, TM...) are characteristics of
>>>>
> the
>
>>>>
>>>>
>>> trace or transmission line and they die exponentially away from the
>>>
> point
>
>>> of excitation, i.e., the via-trace interface. S-parameters, like other
>>> network parameters, give us the relation between input and output
>>>
> signals.
>
>>> Now, to obtain S11, for example, you need to get the ratio of the
>>>
> reflected
>
>>> and input signals. Both signals must be of the same "type". We can not
>>> directly compare cars and aeroplanes, though both are used for
>>> transportation. You know your input signal (e.g., a transverse
>>> electromagnetic wave), because you excited it at the port. At
>>> discontinuities, an infinite order of given higher-order modes can be
>>> excited. The orders or strength of the excited modes differ from one
>>> discontinuity to another, although the modes can be the same. So, there
>>>
> is
>
>>> no way you can know all the orders of the higher-order modes excited and
>>> how they interact. Now if you place your ports quite close to the point
>>>
>>>
>>>> of excitation of these modes, then your S-parameters must be wrong.
>>>>
> Why?
>
>>>>
>>>>
>>> In this case, to obtain S11, you need to obtain the ratio of the unknown
>>> higher-order modes and your known excited transverse electromagnetic
>>>
> wave
>
>>> at the port. That’s why in most 3D full-wave solvers, it is recommended
>>> that ports should be placed far away from the discontinuities, so as to
>>> enable these higher-order modes to die. When they die, then you can
>>>
> easily
>
>>> define your S-parameters which will then be the ratio of the input
>>>
> signal
>
>>> you know (transverse electromagnetic wave) and the reflected signal you
>>> know (transverse electromagnetic wave). To define the points where these
>>> modes die or have attenuated substantially, these authors argued that
>>>
> near
>
>>> the discontinuity, the imaginary part of the Poynting vector describes
>>>
> the
>
>>> reactive energy associated with these higher-order modes. So they
>>>
> studied
>
>>> this imaginary part and used it to define the point where the modes
>>>
> die. I
>
>>> think they mentioned that only
>>>
>>>
>>>> at a distance of about 1mm away from the via-trace interface, at 20
>>>>
> GHz
>
>>>>
>>>>
>>> (or may be 30 GHz) may you place your ports, to get correct results.
>>> Certainly, this depends on the via geometry and trace type. But I find
>>>
> the
>
>>> results very helpful and can be used as a base for further experiments.
>>>
> You
>
>>> can get the details from the paper.
>>>
>>>
>>>> Unfortunately in your case, you compare what you don’t know
>>>>
> (reflected
>
>>>>
>>>>
>>> signal) and what you know (excited input signal). In your via models,
>>> neither did you define the required distance away from the via-trace
>>> interface needed for these modes to die nor did you follow the advice
>>>
> given
>
>>> in full-wave solvers to be far way from the via-trace interface. You
>>> considered the via just as the barrel and the pads at 20 GHz and beyond.
>>> That’s why I mentioned yesterday that your via models are not correct
>>>
> and
>
>>> your S-parameter results are misleading. If you wish to study only the
>>> behaivor of the barrel alone at lower frequencies (for what ever reason
>>>
> -
>
>>> but not for realistic designs), then you don't even need a field solver.
>>> You can get formulas from good SI texts like that of Horward Johnson or
>>> from papers.
>>>
>>>
>>>> At first I was also making the same mistakes as you are making right
>>>>
>>>>
>>> now. I had a lot of difficulties to correlate my simulation and
>>>
> measurement
>
>>> results. So I learnt a lot from this paper, from Professor C. Balanis
>>> (Advanced engineering electromagnetics) and from Professor R. Collins
>>> (Field theory of guided waves). I think these references will be good
>>>
> for
>
>>> you. You need all three of them.
>>>
>>>
>>>> There are also a lot of points that you need to modify in your
>>>>
> models.
>
>>>> It’s ridiculous when you talk of -30 dB attenuation of higher-order
>>>>
>>>>
>>> modes. Which higher-order mode? Which order of this mode? Basic
>>> electromagnetic theory teaches us that an infinite order of a given
>>> higher-order mode can be excited at any discontinuity. An interaction
>>> between makes matters worst. So how do you separate the different
>>>
> orders of
>
>>> the modes and tell which one attenuates by -30 dB? Are the modes
>>> propagating or evanescent? Never use rule of thumbs that have no base. I
>>> supposed you meant attenuation of the fundamental mode which is
>>> propagating.
>>>
>>>
>>>> I don’t know anything about the lumped ports you use. All I know is
>>>>
>>>>
>>> that some lumped ports in some field solvers assume perfect H boundary
>>> conditions on the sides. Consequently, depending you may not even
>>>
> capture
>
>>> stray fields. So you can even get the worst results with lumped ports.
>>>
>>>
>>>> You can only shift your reference S-parameters plane and get accurate
>>>>
>>>>
>>> results if your model captured all the necessary field behavior. But you
>>> can not simulate the via and traces differently and then do some
>>> post-processing or circuit modeling afterwards and expect to get correct
>>> results at higher frequencies. The traces too are part of the “via
>>>
> effect”
>
>>> at least, at the frequencies you are interested in (20 GHz and beyond),
>>> because the stored higher-order modes give rise to additional
>>>
> inductances
>
>>> and capacitances. These inductances and capacitances can not be
>>>
> captured if
>
>>> you analyze the vias separately from their traces.
>>>
>>>
>>>> Finally, the theory of multi-modal decomposition means different
>>>>
> things
>
>>>>
>>>>
>>> to different electrical engineers. So I don’t know what you mean. If you
>>> mean that different parts of a system can be analyzed separately and
>>>
> then
>
>>> put together, then it’s true that it has been done for decades now. But
>>>
> the
>
>>> question is this. How do you bring the different parts together in the
>>>
> case
>
>>> where there are discontinuities like vias? How do you define the via?
>>>
> How
>
>>> small or big is your near field zone? I bet you, we have not yet
>>>
> understood
>
>>> this type of decomposition and it has not been done, or at least
>>>
> published
>
>>> for decades. Whenever we have to deal with vias and other
>>>
> discontinuities
>
>>> at higher frequencies, straight-forward modeling can not be used.
>>>
>>>
>>>> Please Yuryi, don’t get me wrong. I’m not trying to highlight on
>>>>
> your
>
>>>>
>>>>
>>> errors. I have mine too, like any body else. No one is perfect. I’m just
>>> trying to raise the point that we need to be careful when modeling vias
>>>
> at
>
>>> your frequencies. I agree with most of the points you made, but
>>>
> disagree on
>
>>> the ones stated above. We learn from each other when we exchange ideas
>>> about such fundamental issues that affect our modeling results. I think
>>> that is one of the reasons why Ray and his team set up this forum.
>>>
>>>
>>>>
>>>> Best regards.
>>>> Charles
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Yuriy Shlepnev <shlepnev@xxxxxxxxxxxxx> wrote: Charles,
>>>>
>>>> I am sorry that the simulation examples were not helpful to you. I will
>>>> appreciate if you send me the reference you mentioned - I am preparing
>>>>
> to
>
>>>>
>>>>
>>> be
>>>
>>>
>>>> shocked:)
>>>>
>>>> You are absolutely right, the via-holes are not just pads and barrels
>>>>
> and
>
>>>> there is no one solution that covers all possible cases. Analysis of
>>>> different vias has to be done in different ways. Transition to the
>>>>
> traces
>
>>>> have to be almost always included in the final model for analysis of
>>>> multi-gigabit channels. Moreover sometime the via-hole problem cannot
>>>>
> be
>
>>>> solved locally and require analysis of parallel plane structures with
>>>>
> all
>
>>>> decoupling structures attached (see technical presentation #1 at
>>>> http://www.simberian.com/Presentations.php for more details on
>>>>
> different
>
>>>> structures).
>>>>
>>>> Considering the ports and excitation. Analysis of via-holes with lumped
>>>> ports provides just rough idea about the via-hole behavior. It is
>>>>
> similar
>
>>>>
>>>>
>>> to
>>>
>>>
>>>> what you would see from a differential probe attached to the pads of
>>>>
> the
>
>>>> via-holes. Transition to traces and transmission line or wave-ports
>>>>
> have
>
>>>>
>>>>
>>> to
>>>
>>>
>>>> be used for the final extraction of S-parameters for the system-level
>>>> analysis (I am sorry that you missed this part in app notes). Note
>>>>
> that it
>
>>>> is possible only for the localizable via-holes or via-holes not
>>>>
> coupled to
>
>>>> parallel planes in general. Such t-line ports have to be positioned at
>>>>
> a
>
>>>> distance from the via-hole that guaranties that the high-order modes
>>>>
> are
>
>>>> attenuated substantially (for practical applications we usually use
>>>>
> -30 dB
>
>>>> threshold at the highest frequency of interest). After such analysis,
>>>>
> the
>
>>>> phase reference planes of S-parameters can be safely shifted closer to
>>>>
> the
>
>>>> via-hole at the position where t-lines are still continuous to preserve
>>>> causality (to the edges of anti-pads for instance). Such transformation
>>>>
>>>>
>>> does
>>>
>>>
>>>> not affect the near field or high order modes around the via-holes and
>>>>
> the
>
>>>> final model can be safely connected with the transmission line segments
>>>>
>>>>
>>> in a
>>>
>>>
>>>> system-level solver. Though, the model have to be used with
>>>>
> transmission
>
>>>> line segments with length not less than in the electromagnetic analysis
>>>>
>>>>
>>> (to
>>>
>>>
>>>> avoid the near-field interaction between the vias and possible
>>>> discontinuities). This technique called the multi-modal
>>>>
> de-compositional
>
>>>> analysis and used in microwave engineering for decades at frequencies
>>>>
> even
>
>>>> higher than 20 GHz.
>>>> Note, that in typical PCB trace the cut-off frequencies for high-order
>>>>
>>>>
>>> modes
>>>
>>>
>>>> are extremely high. 10 mil trace on 10 mil dielectric with dielectric
>>>> constant 4.2 have cut-off frequency about 120 GHz, and the cross-over
>>>>
> with
>
>>>> the surface TM mode may happen only at 200 GHz. Before 120 GHz the
>>>> high-order modes are evanescent and essentially form the via-hole near
>>>> field. This near-field zone is expanding with the frequency, but at 20
>>>>
> GHz
>
>>>> the area is still relatively small. Thus S-parameters only for the
>>>>
>>>>
>>> dominant
>>>
>>>
>>>> modes can be safely extracted and used as the via-hole model.
>>>> Cases when via-hole excite the non-evanescent parallel-plane modes and
>>>> planes are not stitched close to the via-hole cannot be solved locally
>>>>
>>>>
>>> (non
>>>
>>>
>>>> localizable) and may require the system-level analysis with all
>>>>
> decoupling
>
>>>> structures attached.
>>>>
>>>> Best regards,
>>>> Yuriy
>>>>
>>>> Yuriy Shlepnev
>>>> Simberian Inc.
>>>> www.simberian.com
>>>>
>>>> -----Original Message-----
>>>> From: si-list-bounce@xxxxxxxxxxxxx
>>>>
> [mailto:si-list-bounce@xxxxxxxxxxxxx]
>
>>>>
>>>>
>>> On
>>>
>>>
>>>> Behalf Of Charles Harrington
>>>> Sent: Monday, November 19, 2007 8:33 AM
>>>> To: shlepnev@xxxxxxxxxxxxx; scott@xxxxxxxxxxxxx
>>>> Cc: sunil_bharadwaz@xxxxxxxxx; 'SI LIST'
>>>> Subject: [SI-LIST] Re: Signal crossing Split plane
>>>>
>>>> Yuriy,
>>>> not only are your slot simulations on your page not so helpful, but
>>>>
> your
>
>>>> via simulations are very misleading. I think you'll run into trouble
>>>>
> when
>
>>>> you try to compare your simulation and measurement results, because
>>>>
> your
>
>>>> simulation models are unrealistic.
>>>>
>>>> At such frequencies (20 GHz and beyond), the via can no longer be
>>>>
>>>>
>>> considered
>>>
>>>
>>>> to be just the barrel and the pads, as you did. The modes excited at
>>>>
> the
>
>>>> via-trace interface don't die abruptly, but extend along the traces to
>>>>
> the
>
>>>> ports. So either you seperate these modes from the originally excited
>>>>
>>>>
>>> modes
>>>
>>>
>>>> at the port (in order to obtain "clean" S-parameters') or you allow the
>>>> modes to die before they reach the ports (as recommended in most 3D
>>>> full-wave solvers).
>>>> I just read a very interesting research paper the other day on defining
>>>>
>>>>
>>> the
>>>
>>>
>>>> boundaries of discontinuties, in which these issues are properly
>>>>
>>>>
>>> examined. I
>>>
>>>
>>>> can't really remember the exact title nor its authors at the moment,
>>>>
> but
>
>>>>
>>>>
>>> the
>>>
>>>
>>>> paper was presented at a Ph.D. research conference on microelectronics
>>>>
> and
>
>>>> electronics somewhere in Europe (Italy, I presume). You'll be shocked
>>>>
> at
>
>>>>
>>>>
>>> the
>>>
>>>
>>>> error you are making when you read this work.
>>>> You also connected the models of the via and transmission lines after
>>>>
> the
>
>>>> simulations, correct? Here you go wrong again, because how do you know
>>>>
>>>>
>>> where
>>>
>>>
>>>> the vias "actually" begin and end? And at what freqency? These are very
>>>> complicated issues and I suggest you spend a little more time studying
>>>>
>>>>
>>> them
>>>
>>>
>>>> well.
>>>> Thanks.
>>>> Charles
>>>>
>>>> Yuriy Shlepnev wrote: Scott,
>>>>
>>>> I agree with you. It was just an illustration of a slot-type
>>>>
> discontinuity
>
>>>> in general for some stackup configurations. It shows how a slot-type
>>>> discontinuity in a reference plane may reflect the signal even in the
>>>>
> case
>
>>>> if slot does not cut across the board or around a patch (though, it
>>>>
> might
>
>>>>
>>>>
>>> be
>>>
>>>
>>>> obvious for you). As soon as the coupling to a slot is strong, it has
>>>>
> to
>
>>>>
>>>>
>>> be
>>>
>>>
>>>> simulated at the system level with a complete geometry of the slot or
>>>>
>>>>
>>> split,
>>>
>>>
>>>> with all relevant traces crossing the slot and all de-caps (if any). I
>>>> prefer to do it with the hybrid de-compositional approach on the base
>>>>
> of
>
>>>> localized models built with an electromagnetic solver. The localized
>>>>
> strip
>
>>>> to slot coupling effect can be captured with a 4-port S-parameter model
>>>>
>>>>
>>> for
>>>
>>>
>>>> strip crossing the slot for instance (two ports for the strip and two
>>>>
> for
>
>>>> the slot). Combined with the strip and slot line models, it produces a
>>>> simple and computationally efficient system-level model that captures
>>>> practically all coupling and resonance effects.
>>>>
>>>> Best regards,
>>>> Yuriy
>>>>
>>>> Yuriy Shlepnev
>>>> Simberian Inc.
>>>> www.simberian.com
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: si-list-bounce@xxxxxxxxxxxxx
>>>>
> [mailto:si-list-bounce@xxxxxxxxxxxxx]
>
>>>>
>>>>
>>> On
>>>
>>>
>>>> Behalf Of Scott McMorrow
>>>> Sent: Sunday, November 18, 2007 12:29 PM
>>>> To: shlepnev@xxxxxxxxxxxxx
>>>> Cc: sunil_bharadwaz@xxxxxxxxx; 'SI LIST'
>>>> Subject: [SI-LIST] Re: Signal crossing Split plane
>>>>
>>>> Yuriy
>>>>
>>>> Actually, these sorts of slot simulations are pretty meaningless.
>>>>
> Slots
>
>>>> normally occur due to plane splits. As a result, the either extend
>>>>
> from
>
>>>> one edge of a board to another edge, or when the plane is a square
>>>>
> patch
>
>>>> the slot is a closed loop around the periphery of the plane. When
>>>>
> this
>
>>>> happens, it is quite interesting to simulate multiple signals crossing
>>>> the slot. There is a very nice slot resonance mode that occurs that
>>>>
> is
>
>>>> generally in the signal bandwidth (or at least 3rd harmonic) because
>>>>
> of
>
>>>> the length of the slot. This induces a signficant amount of ringing
>>>>
> and
>
>>>> crosstalk into neighboring traces.
>>>>
>>>> scott
>>>>
>>>> Scott McMorrow
>>>> Teraspeed Consulting Group LLC
>>>> 121 North River Drive
>>>> Narragansett, RI 02882
>>>> (401) 284-1827 Business
>>>> (401) 284-1840 Fax
>>>>
>>>> http://www.teraspeed.com
>>>>
>>>> TeraspeedR is the registered service mark of
>>>> Teraspeed Consulting Group LLC
>>>>
>>>>
>>>>
>>>> Yuriy Shlepnev wrote:
>>>>
>>>>
>>>>> Sunil,
>>>>>
>>>>> A simple example of how an electromagnetic solver can be used to
>>>>>
>>>>>
>>>> investigate
>>>>
>>>>
>>>>> the effect of a slot or split in a reference plane is provided at
>>>>> http://www.simberian.com/AppNotes.php - see the topmost app note.
>>>>>
>>>>> Best regards,
>>>>> Yuriy
>>>>>
>>>>> Yuriy Shlepnev
>>>>> Simberian Inc.
>>>>> www.simberian.com
>>>>>
>>>>> -----Original Message-----
>>>>> From: si-list-bounce@xxxxxxxxxxxxx
>>>>>
> [mailto:si-list-bounce@xxxxxxxxxxxxx]
>
>>>>>
>>>>>
>>>> On
>>>>
>>>>
>>>>> Behalf Of sunil bharadwaz
>>>>> Sent: Sunday, November 18, 2007 1:26 AM
>>>>> To: SI LIST
>>>>> Subject: [SI-LIST] Signal crossing Split plane
>>>>>
>>>>> Hi ,
>>>>> I have few signals (@ 80 Mhz & 20 Mhz) crossing the split Power
>>>>> plane in the adjacent layer.
>>>>>
>>>>> The 20 Mhz signal is diffrerential signal.The 80 Mhz is a single
>>>>> ended signal.
>>>>>
>>>>> I want to analyse the affect on Signal Integrity of these two
>>>>> signals due to split plane.
>>>>>
>>>>> I believe one need to define his stack up (Including the
>>>>> split) & then extract the layout to simulate.
>>>>>
>>>>> I'am not too sure if the prevalent SI tools have an option
>>>>> of creating split planes .
>>>>>
>>>>> Pls suggest me a right tool to carry out this.Also , i'am
>>>>> looking for a free tool to start with (even if the accuracy
>>>>> is slightly limited).
>>>>>
>>>>> Thanks in Advance!!
>>>>>
>>>>> Regards
>>>>> Sunil.Bh
>>>>>
>>>>>
>>>>> ---------------------------------
>>>>> Be a better pen pal. Text or chat with friends inside Yahoo! Mail. See
>>>>>
>>>>>
>>>> how.
>>>>
>>>>
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>>> it
>>>
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>>>> ---------------------------------
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>> --
>> Steve Weir
>> Teraspeed Consulting Group LLC
>> 121 North River Drive
>> Narragansett, RI 02882
>>
>> California office
>> (408) 884-3985 Business
>> (707) 780-1951 Fax
>>
>> Main office
>> (401) 284-1827 Business
>> (401) 284-1840 Fax
>>
>> Oregon office
>> (503) 430-1065 Business
>> (503) 430-1285 Fax
>>
>> http://www.teraspeed.com
>> This e-mail contains proprietary and confidential intellectual property
>>
> of Teraspeed Consulting Group LLC
>
> ----------------------------------------------------------------------------
> --------------------------
>
>> Teraspeed(R) is the registered service mark of Teraspeed Consulting Group
>>
> LLC
>
>> ------------------------------------------------------------------
>> To unsubscribe from si-list:
>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>>
>> or to administer your membership from a web page, go to:
>> //www.freelists.org/webpage/si-list
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>> For help:
>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>>
>>
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>> Old (prior to June 6, 2001) list archives are viewable at:
>> http://www.qsl.net/wb6tpu
>>
>>
>
>
>
>
>
--
Steve Weir
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
California office
(408) 884-3985 Business
(707) 780-1951 Fax
Main office
(401) 284-1827 Business
(401) 284-1840 Fax
Oregon office
(503) 430-1065 Business
(503) 430-1285 Fax
http://www.teraspeed.com
This e-mail contains proprietary and confidential intellectual property of
Teraspeed Consulting Group LLC
------------------------------------------------------------------------------------------------------
Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
