[SI-LIST] Re: DC resistance calculation of returen path_equivalent width?
- From: =?big5?q?sghsu55?= <sghsu55@xxxxxxxxxxxx>
- To: "John Lin (???)" <John@xxxxxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Tue, 5 Nov 2002 16:43:16 +0800 (CST)
John,
Thank you for replying. The keypoint is how to
estimate the DC resistance of return path. For
matching the requirement of voltage drop, I had to
estimate the minimun trace width for conductor.
However, I don't what's the equivalent width of return
path. S. Hall et al. (High-speed digital system
design, pp.80) gave an equaltion and said the
equivalent width of return path is about 6H for AC.
Does the approximation still work as well if
(1) DC case
(2) Signal trace is cruve instead of straight between
driver and receiver.
Thank you in advance.
--- "John Lin (???)" <John@xxxxxxxxxxxx> ���T���G>
Sogo,
> Nice to hear you again on this list.
>
> if the DC resistance is what you mentioned, then the
> whole ground plane will be your return path. For low
> frequency, the return current distributes widely
> all over the ground plane.
>
> Best Regards,
>
> John Lin
>
> Quanta Computer Inc.,Taiwan, R.O.C.
> Email: John@xxxxxxxxxxxx
> Tel: 886+3+3272345 ext. 5183
>
>
>
>
>
> -----Original Message-----
> From: Sogo Hsu [mailto:sghsu55@xxxxxxxxxxxx]
> Sent: Monday, November 04, 2002 10:22 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] DC resistance calculation of
> returen path_equivalent width?
>
>
>
> Hi SI gurus,
> I have a question regarding DC resistance
> calculation of return
> current path. It is said the return current path
> would be the least-
> length path between driver and receiver. At this
> moment, I would like
> to estimate the required trace with to match voltage
> drop spec, for
> instance, USB 2.0. For conductor signal trace, the
> DC resistance
> would be
> Rho * L/ (W*t),
> but what=A1=A6s the equivalent width for return
> path? Thank you in
> advance.
> Best regards,
> Sogo Hsu
>
>
>
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