> When you say "harmonic frequency", do you mean the > output frequency of PLL? Most of the time the output > frequency is much higher than the PLL's filter bandwidth, > which is usually in the hundreds of kHz. PLLs tend to > be sensitive to noise on their analog supply pin at or > below the filter bandwidth. Have you also compared the > noise below 1MHz? I overlooked this too. Istvan is right. On the assumption that noise on the filtered power might be affecting the PLL, the noise you should be looking for is in the kHz (sub-MHz) range. Regards, Andy ------------------------------------------------------------------ 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