Dear Kedar The following is my advice. 1.up to 150MHz The decoupling capacitor is important. The fanout should be careful. Via in pad is very good. However we seldom use this kind of technique. I think the separation between the two vias should be cared because it will determine the ESL. 2.150MHz to 500MHz Maybe the embedded caps should be applied. The anti-resonance between the discrete caps and embedded caps should be cared. In our boards, there is the similar situation, that at some frequency, the noise in embedded PCB is larger than that in the common PCB. 3.above 500MHz There is nothing to do with the PCB:( Hope this is helpful. Best Regards Zhangkun 2006.1.19 ----- Original Message ----- From: "Kedar P Apte" <kedar.apte@xxxxxxxxx> To: <si-list@xxxxxxxxxxxxx> Sent: Thursday, January 19, 2006 1:17 PM Subject: [SI-LIST] Decoupling Cap. Strategies. > Hi All Gurus, > > What are the different decoupling capacitor placement and routing > strategies for high speed boards...? > If you specifically make a band of high frequencies like > 1. up to 150 MHz. > 2. 150 to 500 MHZ > 3. 500 MHz and above. > > I can understand that for 50MHz and above designs every thing will be cross > calculated and possibly simulated before finalizing. > > I just want to ask that for any design the strategy of putting a via to a > power plan directly on the Capacitor Pad will work fine...? or there has to > be some calculation and evaluation of the decoupling strategy for every > design. > > Please if anybody can suggest any guidelines or documents it will be very > helpful. > > I am getting many things on the net also and getting guideline documents > from the chip manufacturers as well but a good discussion will always help > me to finalize my strategic goal. > > Thanks & Regards, > Kedar > > > http://www.patni.com > World-Wide Partnerships. World-Class Solutions. > _____________________________________________________________________ > > This e-mail message may contain proprietary, confidential or legally > privileged information for the sole use of the person or entity to > whom this message was originally addressed. Any review, e-transmission > dissemination or other use of or taking of any action in reliance upon > this information by persons or entities other than the intended > recipient is prohibited. If you have received this e-mail in error > kindly delete this e-mail from your records. If it appears that this > mail has been forwarded to you without proper authority, please notify > us immediately at netadmin@xxxxxxxxx and delete this mail. > _____________________________________________________________________ > > > ------------------------------------------------------------------ > 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