On Fri, 2003-08-01 at 14:50, Ray Anderson wrote: > With all due respect to the UMR authors, I think the location > of a decap on a set of power planes DOES matter. [...] And the UMR authors agree. From the Summary of their paper*: "A lumped element model has been developed for decoupling on a multilayer PCB. The model is valid for frequencies below the distributed resonances of the power bus, which for PCBs on the order of 6-10" is approximately 200-300MHz." and "Experimental results show that the location of the decoupling capacitor is not critical to performance in the frequency range below several hundred megahertz (where a lumped element model is valid)." *Drewniak, J.L., Hubing, T.H. et al, Modeling Power Bus Decoupling on Multilayer Printed Circuit Boards, 1994. -- ============================================================================= Mike Mayer mwmayer@xxxxxxx ------------------------------------------------------------------ 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 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