Sogo I have read the paper long long ago : ) That paper gives rise to my method and Istvan also give me a lot of help and instruct. It is possible to match the impedance of radial transmission line. In FDTD algorithm, there is one absorbing boundary condition named Mur's. My method is similar to that. I have made testing board and compared simulation and measurement. Best Regards Zhangkun 2004.12.3 ----- Original Message ----- From: "Sogo Hsu" <sogo.hsu@xxxxxxxxxxx> To: <si-list@xxxxxxxxxxxxx> Sent: Friday, December 03, 2004 4:14 PM Subject: [SI-LIST] Re: Why is capacitor with high ESR > > 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: > > //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: > > //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: > //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 > > ------------------------------------------------------------------ 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