IT DEPENDS, is the most definitive answer that we can offer for this
question. It would vary based on the impedance of the trace which is a
function of material, trace width and plane separation.


Jeffrey A McGlaughlin, CID
Engineering Designer
Battelle Memorial Institute
Columbus Ohio
http://www.battelle.org
[log in to unmask]

-----Original Message-----
From: Jack C. Olson [mailto:[log in to unmask]] 
Sent: Thursday, December 02, 2004 1:55 PM
To: [log in to unmask]
Subject: [DC] Return Current Path vs. Frequency

Return Current Path vs. Frequency

-=-=-=-
Easy question:

Imagine a "U"-shaped trace above a solid ground plane,
with a connection at each end.

Inject a signal through the "U", and vary the frequency.

At what frequency will you see the return current
follow the shape of the U rather than the shortest path?

-=-=-=-
Bonus question:

What if I replace the ground plane with a power plane?
(I say it makes no difference. )

thanks,
Jack (the "arguing with a new engineer" guy)

------------------------------------------------------------------------
---------
DesignerCouncil Mail List provided as a free service by IPC using
LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text
in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET
DesignerCouncil NOMAIL/(MAIL)
Search previous postings at: www.ipc.org > On-Line Resources & Databases
> E-mail Archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
------------------------------------------------------------------------
---------

---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL)
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
---------------------------------------------------------------------------------