[SI-LIST] Current Return Path
- From: kfrobinson@xxxxxxxxxx
- To: <si-list@xxxxxxxxxxxxx>
- Date: Thu, 26 Jun 2003 09:43:07 -0600
All,
I was recently evaluating a board design and noticed that some signals =
were referenced to a power plane(VTERM) and some nets were referenced to =
ground. This is a very large board 13" x 22" and there are bypass caps =
between the power plane and ground plane around the perimeter of the =
board. I thought I would see if I could destroy the current return path =
by removing all the bypass caps between the power plane and ground plane =
except from the far end of the board furthest from the driver. I then =
looked at the signals that were referenced to the power plane and they =
were identical to what they had been before the removal of caps. I =
took scope shots at multiple locations before and after the cap removal. =
The net in question runs the length(22") of the board right down the =
center. I had expected to see a pronounced change, but did not see one. =
Any thoughts?
Stack up
s
vterm
s
s
vcc
gnd
vcc
gnd
s
s
gnd
s
Ken Robinson
kfrobinson@xxxxxxxxxx
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