[SI-LIST] 回复:RE: Re: mode conversion myth
- From: liuluping 41830 <liuluping@xxxxxxxxxx>
- To: shlepnev@xxxxxxxxxxxxx
- Date: Sun, 04 Jan 2009 15:34:05 +0800
Thank you for your new year gift, I will study it carefully:)
As steve suggested, "lace length compensation features as close to geometry
that disturbs length match as possible. " ,but how close is enough?
This papaer may be helpful on this problem:
"Noise Reduction Using Compensation Capacitance for Bend Discontinuities of
Differential Transmission Lines",Guang-Hwa Shiue etc.,
IEEE TRANSACTIONS ON ADVANCED PACKAGING, VOL. 29, NO. 3, AUGUST 2006
发件人: Yuriy Shlepnev <shlepnev@xxxxxxxxxxxxx>
日期: 星期日, 一月 4日, 2009 上午5:19
主题: RE: [SI-LIST] Re: mode conversion myth
收件人: 'liuluping 41830' <liuluping@xxxxxxxxxx>, Istvan.Novak@xxxxxxx,
eric@xxxxxxxxxxxxxxx
抄送: si-list@xxxxxxxxxxxxx, si-list@xxxxxxxxxxxxx
> Liu,
>
> Istvan provided some general guidance on how to handle the skew or
> modetransformation that may cause the skew. I think to be more
> specific you have
> to run your favorite electromagnetic solver and estimate the
> amount of the
> mode transformation and what it does to the signal. It may require a
> compensation or may not. Some examples of such analysis are
> provided in App
> Note #2009_01 at http://www.simberian.com/AppNotes.php Note, that
> to verify
> the theoretical concepts of the mode transformation and compensation,
> Teraspeed Consulting Group provided experimental results from
> their PLRD-1
> test board.
>
> Best regards,
> Yuriy Shlepnev
> www.simberian.com
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-
> bounce@xxxxxxxxxxxxx] On
> Behalf Of liuluping 41830
> Sent: Friday, January 02, 2009 12:12 AM
> To: Istvan.Novak@xxxxxxx; eric@xxxxxxxxxxxxxxx
> Cc: si-list@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: mode conversion myth
>
> Dear Eric and Istvan:
>
> Yes ,"do not introduce any local skew" ,Istavan's
> clarification is very
> helpful in practical design,
> and I also have myth on this problem: How to compensate for the
> local skew ?
>
> For example ,the bend discontinuities of differential
> pairs,the msot
> common practical routing scheme
> using a small detour for the inner trace of coupled bends,but does
> thiscompensation affect the common
> mode noise?
> Some paper suggest different routing schemes like shunt a
> compensationcapacitance at the bends,
> but it's not very practical to use, Can we find better ways?
>
> Thanks and happy new year!
>
> LIU Luping
>
>
>
>
> Msg: #5 in digest
> Date: Tue, 30 Dec 2008 16:59:03 -0500
> From: istvan Novak <Istvan.Novak@xxxxxxx>
> Subject: [SI-LIST] Re: mode conversion myth
>
> Hi Eric,
>
> Yes, in general I agree with your description, I would add one
> clarification, though. With a spatial resolution determined by
> the
> bandwidth of signal we want to push through the differential
> interconnect, we need to keep the electrical symmetry between the
> legs
> all along the way. In particular, when it comes to propagation
> delay,
> it is very important that not only the end-to-end propagation
> delay is
> kept similar, but we do not introduce any local skew. This
> becomes
> important when we have to decide where and how we compensate for
> known
> skew contributors.
>
> Regards,
>
> Istvan
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