Hi Steve, As I understand the spec, these are differential strobes with timing referenced to the zero crossing of the true and complement. This is how TriCN implements the DDR 2 strobe in our IP. Jedec's most recently released document muddied the waters a bit when they revised the pindescription to say "... The data strobes DQS, LDQS, UDQS, and RDQS may be used in single ended mode or paired with optional complementary signals DQS, LDQS, UDQS, and RDQS to provide differential pair signaling to the system during both reads and writes...." The spec used to just refer to a "differential strobe" which is certainly more clear. Complementary signaling, at least as I define it, is found in the RLDRAM specs which are modeled after QDR SRAM specs. Here the timing of the DQ is measured to the rising edges of the DQS and DQS# ( Or K and K# with SRAMs). DQS and DQS# are treated as separate strobes, nominally 180 degrees out of phase in complementary signaling. Hope this helps. John Ellis Vice President Interconnect Technology TriCN, Inc. 3605 Vartan Way Suite 301 Harrisburg, PA 17110 Phone:717-657-1002 Fax: 717-221-1185 email:jellis@xxxxxxxxx www.tricn.com This email message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Steven M. Waldstein Sent: Monday, October 13, 2003 7:35 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] DDR-2 DQS Now that I see that DDR-2 questions are being asked I've got mine to ask. On the current DDR-2 specifications they show "differential" DQS as an improvement to improve timing accuracy. Can anyone tell me if these are really "differential driver and/or receivers" on the memories or are these really complimentary strobes? My reason for asking is that the I often see them referred to as differential but the terminations appear to more representative of a complimentary implementations. Also, most of the IP available from vendors to implement the controller are complementary implementations. I want to make sure these are the proper implementation. Any personal experience would be helpful. Thanks in advance. Steve Waldstein swldstn@xxxxxxxxxxxx ------------------------------------------------------------------ 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 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 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