[SI-LIST] Re: Question regarding return current in a differential pair
- From: <zc@xxxxxxxxxxx>
- To: <mkotson@xxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Thu, 20 Apr 2006 12:55:48 -0400
Hi Mike:
You can put it this way:
(+) signal has its own return current on the reference plane, and at the
same time (-) signal has its on return current on the reference plane, but
the return currents for each signal have opposite directions on the
reference plane. Thus when the differential lines are very close to each
other, the return currents are canceled by each other due to the opposite
directions. Therefore, it seem the return current is flowing back from the
other line.
Hope it is clear for you.
Best,
Zhenggang
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Zhenggang Cheng
Ph.D Candidate
Electrical and Computer Engineering Department
Duke University
FedEx/UPS: Hudson Hall 05C fax: 919-660-5293
US Mail: P.O. Box 90291
Durham, NC 27708
ph: 919-660-5232 (O); 919-218-5520(H)
----- Original Message -----
From: "Michael Kotson" <mkotson@xxxxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Thursday, April 20, 2006 12:46 PM
Subject: [SI-LIST] Question regarding return current in a differential pair
> Hello Gurus,
> I have a question regarding the return current for a high speed
> differential signal. I've seen a couple of sources that state that all
> of the signal return current is handled by the other half of the
> differential pair. It seems more logical to me that there must be some
> amount of return current (not just common mode) on the reference
> plane(s) as well. What's the truth?
>
>
>
> Thanks in advance,
>
> Mike
>
>
>
> Michael Kotson
>
> Project Engineer
>
> VT Miltope
>
> 4900 Pearl East Circle Suite 106
>
> Boulder, CO 80301
>
> (303) 473-0388 x132
>
> http://www.miltope.com <http://www.miltope.com/>
>
>
>
>
>
>
>
>
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