istvan and steve I want to add some comments on this topic. 1.The power delivery system, which uses traces not plane, will have some defect for the leading inductance. We have done a lot of simulation about the leading inductance of decoupling capacitor. When the trace is taken placed by plane, the ESL gets less of about 6db. 2.The resonance about power plane could be eliminated by means of some effort. The frequency could be extended to about 1GHz or higher. However, in some product PCB, there is no space for this kind of measures. The PCB is too crowded. AVX has provided some high-ESR capacitor, whose ESR could be as large as 100 ohm. 3.Using trace for power delivery could be used for some special circuit such as PLL. There are some paper in IEEE International Symposium on EMC 2003 on this topic. Best Regards Zhangkun 2004.8.27 ------------------------------------------------------------------ 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