[SI-LIST] Re: Why crosstalk calculation does not count into trace width?
- From: "Hargin, Bill" <bill_hargin@xxxxxxxxxxx>
- To: "'Ho.Jeff@xxxxxxxxxxxx'" <Ho.Jeff@xxxxxxxxxxxx>,Allen_Wang@xxxxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Wed, 22 Oct 2003 21:45:13 -0700
Hi Allen:
Wider traces increase capacitive coupling with the adjacent reference plane.
With the Widths and Spacing you've outlined it's hard to see the difference,
though. The trace is coupling so closely to the plane that it's hardly coupled
to the victim which is 15 mils away. If you move the traces closer together,
and make the width difference more significant (for comparison), it's easy to
see the trace-to-trace coupling (crosstalk) difference.
<<...OLE_Obj...>>
W = 8 mils, Spacing = 5 mils; blue e-field lines show coupling to plane;
Obviously, at 15 mil spacing the coupling (crosstalk) would be even lower.
<<...OLE_Obj...>>
W = 5 mils, Spacing = 5 mils; blue e-field lines show relatively stronger
coupling between traces due to reduced coupling with the plane.
(Screen shots from LineSim.)
Bill Hargin
Mentor Graphics Corp.
Systems Design Division
High-Speed Tools
425-497-5079 - Direct
425-301-4425 - Mobile
> -----Original Message-----
> From: Ho.Jeff@xxxxxxxxxxxx [mailto:Ho.Jeff@xxxxxxxxxxxx]
> Sent: Wednesday, October 22, 2003 8:05 PM
> To: Allen_Wang@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Why crosstalk calculation does not
> count into trace width?
>
>
> Hi Allen,
> The trace width involve in the distance "D".
> Based on same configuration and just vary the trace width, I
> found trace width is relative to coupling effect.
> It shows high impedance traces(thinner) have more coupling influence.
> Attached file listed below for your reference.
>
> Regards,
>
> Jeff
>
> -----Original Message-----
> From: Allen_Wang@xxxxxxxxxxx [mailto:Allen_Wang@xxxxxxxxxxx]
> Sent: Wednesday, October 22, 2003 7:06 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Why crosstalk calculation does not count into trace
> width?
>
>
> Dear all:
>
> It's me again. Thanks Steve first to provide us good
> explanation of our =
> last question....
>
> We then come out another one that in crosstalk calculation, why the =
> trace width does not be counted in..
> For example, in Dr. Howard Johnson's first book page 192, there wrote:
> Crosstalk ~ K / (1 + (D/H)*(D/H)), where D: distance between
> two traces =
> center to center. H: height above the reference plane
>
> In real application, a pattern of 4.5/15 (trace width 4.5 and
> space 15) =
> will really have larger crosstalk than 5/15? (say the H is 4.1mil)
>
> Best regards!
>
> Allen Wang
> ASUSTeK Computer Inc.
> RD8- server centric division
> Manager
> Mobile: 886-935481831
> TEL: 886-2-28943447 ext:3102
> FAX: 886-2-28907689
>
>
> ------------------------------------------------------------------
> 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 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
>
>
>
> -- Binary/unsupported file stripped by Ecartis --
> -- Type: application/vnd.ms-excel
> -- File: test.xls
> -- Desc: test.xls
>
>
> ------------------------------------------------------------------
> 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 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
>
>
------------------------------------------------------------------
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 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:
