Hello Leon, For SSO (Simultanious switching outputs) this does not help, as they will be aligned to the DQS anyhow. For the input noise on DQ this might improve situation a little bit for VDDQ noise, but I don't think you have so much margin that this really changes a lot. Of course this depends on your system speed, but usually timing margins are tight and you don't want to loose too much timing margin. On CA usually you do have a VTT plane which should not impact e. g. VDDQ too much from a noise point of view. So also here I expect that you loose more margin when doing non equal routing vs. SSN noise. ==> My expectation is, that with the small Window that you can use to optimize SSN you will not really gain anything from a noise point of view, but you will loose timing margin. ==> I would not recommend to do it and stay with a reasonable length matching accuracy. Hermann P.S. but I have seen Designs being killed by over-accurate length matching .. Sometimes a not so perfect matching is better than a very tight matching, but this depends on your system. **** Attention: Our Address has changed. Please change your database according to the information below ***** Our next Events: ================ Visit us on Embedded World 2013 in Nuremberg 26-28.02.2013 Hall 1, Booth 430 Check our website or contact us for details EKH - EyeKnowHow Hermann Ruckerbauer www.EyeKnowHow.de Hermann.Ruckerbauer@xxxxxxxxxxxxx Itzlinger Strasse 21a 94469 Deggendorf Tel.: +49 (0)991 / 29 69 29 05 Mobile: +49 (0)176 / 787 787 77 Fax: +49 (0)3212 / 121 9008 schrieb 李磊: > hi, experts, > in many vendors' SDRAM layout guide line, there is equal length requirement > for SDRAM group signals. in order to meet this, we use snake lines to reach > this target usually. > in my understanding, this kind of requirement is just only from electrical > timing point of view. > Actually from SSN point of view, different signal length should have benefit > on the contrary. > so as long as signal timing constraint is not violated, it's better to make > signal length unequal. > > Am I right? > > thanks. > BR,Leon > ------------------------------------------------------------------ > 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