[SI-LIST] Re: Why is capacitor with high ESR
- From: zhangkun 29902 <zhang_kun@xxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Wed, 08 Dec 2004 07:46:52 +0800
Dear all
This morning, I spend half one hour to review all the mail about this topic.
According to my experience, there is the following views:
1.Dency via will not absorb or scatter the EM energy. We have made testing
PCB to study this problem. When there is no decoupling caps, the dency via will
affect the resonance. While there is decoupling caps on the PCB, the effect of
dency via could be ignored. In DesignCon 2004, we have proposed one paper.
2.Via along the edge of PCB will not help to eliminate the far field EMI.
The via has no effect on reflecting EM energy unless the power and ground plane
is connected by via. The voltage source will be shorted. We have made testing
PCB to study this problem.
3.Steve and Chris have proposed seven cases about the PCB decoupling. We
have measured almost the seven cases. The result is that the caps with high ESR
help on eliminate power ground noise.
4.I have done some simulation about SI+PI. I do not see any great difference
when the signal referenced to power or ground. There is a little difference
because of the displacement current. I think power and ground are same but the
voltage potential.
Best Regards
Zhangkun
2004.12.8
------------------------------------------------------------------
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 FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
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:
