Tang: Thanks for the information. One major problem with it, is the different termination impedance for DC-AC range. If the data is not well coded, like 8B/10B, then could cause problem. Thanks again for the inputs. Han George Tang <gtang@xxxxxxxx> wrote: Han, I have not worked on DDR memory design for over 5 yrs, and I don't remember what we did before, so don't take my word for it. However, here is something to think about. Do an AC 60 ohm termination to gnd with a 1k pullup and 1k pulldown for the DC voltage bias. ^ | 1K Driver -->-----------------| | | Z | | 1K = | | | V V George -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Bi Han Sent: Thursday, August 25, 2005 8:17 AM To: List` Si Subject: [SI-LIST] SSTL termination resistor power SSTL termination might use ODT termination for receiver side. The implementation is about 120ohm between PAD and VDDQ, another 120ohm between PAD and VSSQ. Overall AC impedance is about 60ohm. Since signal is DC coupled, there is DC current burning in terminaion resistors. If the PCB trace impedance is 60ohm, then the DC current in the termination resistor is about 20mA. It is so huge that I can not believe that DDR memory can afford it. Is there any way to reduce the power? thanks, Han --------------------------------- Start your day with Yahoo! - make it your home page ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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 --------------------------------- Do you Yahoo!? Yahoo! Mail - You care about security. So do we. ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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