Hello Ravinder, It all depends on the required performance targets for each IO or collectively as a whole at the Asic chip. First you will need to understand the amount of switching current and edge rate that could be present in the package and determine if you can live with one uniform plane with all the IO switching or you may need to have multiple planes if noise levels cannot be met. Second there is the issue of isolation of board noise (lower frequency) making into the package and disrupting sensitive circuits. Typically you can get better isolation with separate planes but this is a trade off with increased board complexity. Generate Z11 and S21 curves from DC to daylight at the chips IO for both cases (some assembly required, decoupling optimization and on-chip caps) and the numbers should point you in the right direction. Regards, -Jory ________________________________ From: "Ravinder.Ajmani@xxxxxxxxxxxxxx" <Ravinder.Ajmani@xxxxxxxxxxxxxx> To: si-list@xxxxxxxxxxxxx Sent: Fri, November 12, 2010 5:48:25 PM Subject: [SI-LIST] Splitting the power plane Hi Experts, Our ASIC vendor advises splitting the power plane between DDR I/Os and other I/Os using a ferrite bead and bulk capacitance. I prefer not to slice the power plane unless it is between Analog and Digital sections of the chip. I will appreciate suggestions from you on this subject. Thanks. Regards, Ravinder Ajmani Server PCB Development Hitachi Global Storage Technologies Email: Ravinder.Ajmani@xxxxxxxxxxxxxx ------------------------------------------------------------------ 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 technical documents are available at: http://www.si-list.net 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 technical documents are available at: http://www.si-list.net 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