FreeLists / si-list / [SI-LIST] Re: Why is capacitor with high ESR

["Sogo Hsu" <sogo.hsu@xxxxxxxxxxx>]

Zhangkun,

Several years ago, I also tried to "match" the impedance. Ideally, 
it is possible, however, it is hard to "match" the characteristic 
impedance of "radial transmission line". Besides, you can find the 
related paper in IEEE. "Reducing simultaneous switching noise and 
EMI on ground/power planes by dissipative edge termination" by Novak.

Best regards,

Sogo Hsu, Ph. D.

Simulation center/Foxconn

--- In si-list@xxxxxxxxxxxxxxx, zhangkun 29902 <zhang_kun@xxxx> 
wrote:
> Dear ALL
> 
> I am incharge of power integrity(PI) and electromagnetic inference
(EMI) in Huawei Tech. In printed circuit board(PCB), the power 
ground plane pair composes of one resonant cavity, which could be 
studied by means of 2-dimension tansmission line theory.
> 
> According to the transmission line theory, when the transmission 
line is matched, there is no resonance. At the edge of PCB, the EM 
energy is reflected because the transmission line is OPEN. 
Traditional decoupling capacitors are of low ESR, which could not 
damping the resonance. Therefore I need capacitor with high ESR, 
whose ESR should be matched with the transmission line. On the other 
hand, the ESL is critical at high frequency. The ESL should be as 
small as possible. The package of capacitor mainly determines ESL so 
that the package should be as small as possible, such as 0402 or 
0603. The capacitance should be as large as possible so that some 
benifit could be gotten at lower freqeuncy domain.
> 
> In DesignCon 2005, Cadence and Huawei will present one paper on 
this topic. The measurement results showed that the power ground 
noise is reduced about 10db and the far field EMI is reduced about 
5db at several hundred MHz, when the capacitor of high ESR is 
applied. The frequency domain is extended to 1GHz where all the 
power ground noise and far field EMI could be reduced.
> 
> Best Regards
> 
> Zhangkun
> 2004.12.3
> 
> 
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxx with 'unsubscribe' in the Subject field
> 
> or to administer your membership from a web page, go to:
> http://www.freelists.org/webpage/si-list
> 
> For help:
> si-list-request@xxxx 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:     
>               http://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



------------------------------------------------------------------
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:
http://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:     
                http://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