Hi Doug, I did not mean to offend you by my reply, and if I did, I apologize. I was just trying to point out the experiences that I had with my simulations. Wayne -----Original Message----- From: Doug Brooks [mailto:doug@xxxxxxxxxx] Sent: Thursday, May 23, 2002 1:33 PM To: Wayne Cooke Subject: RE: Decoupling capacitors At 01:13 PM 5/23/2002 -0400, you wrote: Hi Doug, I read your article, and tried out the decoupling capacitor program you have on your website. What concerns me is that while it is possible to reduce the resultant impedance of certain frequencies by combining different capacitor values, you will be making another group of frequencies worse. In the capacitor combinations that I simulated with, the frequencies above the resulting parallel resonance point were improved, at the expense of the frequencies below the parallel resonance point. Since I don't believe you have purchased a license for the calculator, you were only able to simulate over a very limited range of values. But as the article points out, with a reasonable number of caps, properly chosen, you can achieve an arbitrarily low impedance curve at any and ALL frequencies. The figures in the article also illustrate that. It is true that selecting another value shifts peaks and troughs, but it is also true that adjacent values interract. And this INTERACTION can be used to advantage. Doug UltraCAD Design announces availability of its new book "Signal Integrity Issues in PCB Design" Details at www.ultracad.com <http://www.ultracad.com/> ------------------------------------------------------------------ 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 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