Hi Steve, thanks for the answer (also to the others who responded) ! Good that you have no time machine, otherwise I might be beaten for the AC/DC based setup/hold requirements of the DRAMs ... but I guess there is no danger, as there is enough distance between us ;-) Hermann Our next Events: ================ "Open the Black Box of Memory" Seminar on 08/09. November 2012 Check our website or contact us for details EKH - EyeKnowHow Hermann Ruckerbauer www.EyeKnowHow.de Hermann.Ruckerbauer@xxxxxxxxxxxxx Veilchenstrasse 1 94554 Moos Tel.: +49 (0)9938 / 902 083 Mobile: +49 (0)176 / 787 787 77 Fax: +49 (0)3212 / 121 9008 Am 17.09.2012 23:23, schrieb steve weir: > For most current generation SERDES applications many ordinary MLCCs do > just fine provided that you optimize the transition, pad, and anti-pad > geometries for maximum transparency. There are differing schools of > thought with regard to whether or not one is better off choosing a > capacitor that is filled-out resulting in a thin cover layer, or one > uses a capacitor that has a relatively thick cover layer. Arguments for > the former concentrate on the electrical superiority of that choice, > while arguments for the latter concentrate on the supply source > stability of the latter. Economics dictate that today's thin cover > layer capacitor, is tomorrow's thick cover layer capacitor. > > If I had a time machine I would go back and beat the engineering > ramifications of channel percentage bandwidth into the PC-SIG folks who > designed PCI-Express, forcing us into ridiculously large coupling caps, > and VCO stability requirements. The time for that is far behind us, so > we have to live with these things. 0201s are now available in large > enough capacitances to meet the spec. > > Steve. > > On 9/17/2012 1:20 PM, Hermann Ruckerbauer wrote: >> Hello Rohit, >> >> thanks for the answer, and sorry for my bad description. >> >> I hope to clarify what I ment: >> Any kind of Capacitor that is specially designed for AC-Coupling >> (DC-Blocking) for a specific application (PCIe, SATA, ...) e.g. : >> - low ESR/ESL caps / high Q caps / controlled ESR caps >> - Special material >> - size other than 0402 (e. g. 0201 or reverse geometry) >> - Special designed to have the impdeance minimum fitting to the >> application (I have no idea how to fit 10MHz from plot in the link below >> to e.g. 3GHz of a SATA interface). >> - ... ???? >> >> I found a lot of documents dealing with Capacitors for PDN, but not too >> much for Capacitors used as AC-coupling in serial link applications. >> e. g. www.murata.com/products/article/pdf/ta1082.pdf >> >> Currently I can optimize my board e. g. in order to avoid the >> Capacitance of the pads, but I have somehow no idea whether I can use >> some optimized capacitors as AC-Coupling of a SATA or PCIe interface .. >> >> Any feedback welcome .. >> >> Hermann >> >> >> >> Our next Events: >> ================ >> >> "Open the Black Box of Memory" >> Seminar on 08/09. November 2012 >> >> Check our website or contact us for details >> >> EKH - EyeKnowHow >> Hermann Ruckerbauer >> www.EyeKnowHow.de >> Hermann.Ruckerbauer@xxxxxxxxxxxxx >> Veilchenstrasse 1 >> 94554 Moos >> Tel.: +49 (0)9938 / 902 083 >> Mobile: +49 (0)176 / 787 787 77 >> Fax: +49 (0)3212 / 121 9008 >> >> Am 13.09.2012 12:38, schrieb Rohit MISHRA: >>> Hello Hermann, >>> >>> I don't know what do you mean by "special AC coupling capacitors" but there >>> was a paper from Yaochao Yang & his team in DesignCon 2012, Titled " >>> Embedded DC Blocking Capacitors in Connectors - Study of Impacts on PCB >>> Design" >>> >>> You can have a look, May be you can find what you are looking for. >>> >>> Rgds, >>> Rohit >>> >>> >>> >>> -----Original Message----- >>> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On >>> Behalf Of Hermann Ruckerbauer >>> Sent: Thursday, September 13, 2012 2:34 PM >>> Cc: SI LIST >>> Subject: [SI-LIST] AC coupling capacitors (SATA, PCIe) >>> >>> Hi, >>> >>> i have done a short search on special AC coupling capacitors for serial >>> interfaces (PCIe, SATA, .. ) , but found nothing really special. >>> I have found Steves DesignCon 2012 presentation, but this deals more >>> with characterization than performance requirements. >>> >>> Is there something better available, than a standard C0G/X7R capacitors ? >>> >>> Thanks for any feedback .. >>> >>> Hermann >>> >>> Our next Events: >>> ================ >>> >>> "Open the Black Box of Memory" >>> Seminar on 08/09. November 2012 >>> >>> Check our website or contact us for details >>> >>> EKH - EyeKnowHow >>> Hermann Ruckerbauer >>> www.EyeKnowHow.de >>> Hermann.Ruckerbauer@xxxxxxxxxxxxx >>> Veilchenstrasse 1 >>> 94554 Moos >>> Tel.: +49 (0)9938 / 902 083 >>> Mobile: +49 (0)176 / 787 787 77 >>> Fax: +49 (0)3212 / 121 9008 >>> >>> >>> ------------------------------------------------------------------ >>> 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 forum is accessible at: >>> http://tech.groups.yahoo.com/group/si-list >>> >>> List archives are viewable at: >>> //www.freelists.org/archives/si-list >>> >>> 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 forum is accessible at: >>> http://tech.groups.yahoo.com/group/si-list >>> >>> List archives are viewable at: >>> //www.freelists.org/archives/si-list >>> >>> 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 forum is accessible at: >> http://tech.groups.yahoo.com/group/si-list >> >> List archives are viewable at: >> //www.freelists.org/archives/si-list >> >> 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 forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu