Bala, One reason for the larger spacing between byte lanes is that byte lanes can be routed at different lengths and there can be significant phase offset between byte lanes. Not so much in DDR2, but certainly in DDR3. Out of phase xtalk is more problematic that xtalk within a byte lane. Since there are only 7 boundaries between byte lanes its common to allocate more spacing to these boundaries in order to avoid or reduce out of phase xtalk. Brian Moran Memory Interface Technology Client Platforms Intel Corporation -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of bala Sent: Sunday, July 28, 2013 2:25 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] DDR2 spacing rule Hi All, Why data lines of same byte in ddr2 routed together?As we know all the data lines in a DDR2 running at same frequency and if we route byte0 and byte1 at same length,why do we need to maintain different trace-trace spacing for same byte and different byte? -- bala ------------------------------------------------------------------ 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