Fast Henry is free. Steve. At 02:52 PM 5/23/2006, Narasimhan, Sarath (Sarath) wrote: >I'm searching for an accurate highspeed design model of vias traces >bends routes over split planes in HSPICE. I'm trying to do pre-layout >simulations of high speed signals reaching 10G.Is what I'm trying to >do correct or do I need a tool like Ansoft. Is anyone aware of any >open source high speed design tool that runs on Linux or Unix. > > >-----Original Message----- >From: si-list-bounce@xxxxxxxxxxxxx >[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Chris Cheng >Sent: Tuesday, May 23, 2006 4:34 PM >To: si-list@xxxxxxxxxxxxx >Subject: [SI-LIST] Re: is clock pair-to-clock pair matching required in >DDR? > > >In the read path when you cross a 2x speed DDR path to the 1x common = >clock boundary, you inheritedly have to have a least an elastic buffer = >of one transfer cycle. Since the capture of the data is guarantee by the = >DQ/DQS relationship, the difference (not the absolute value) of DQS = >dealy (hence clock length) just need to fit within a transfer cycle. = >That's a huge tolerance for a point to point net length. I still don't = >understand why you need to match clock/DQS lengths between DQS/Clock = >groups with tight tolerance, especially with a point to point topology = >as stated. > >-----Original Message----- >From: si-list-bounce@xxxxxxxxxxxxx >[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Peterson, James F >(FL51) >Sent: Tuesday, May 23, 2006 11:15 AM >To: si-list@xxxxxxxxxxxxx >Subject: [SI-LIST] Re: is clock pair-to-clock pair matching required in >DDR? > > >=3D20 >yes, for our DDR SDRAM design it was necessary (note: ours did not >include a Freescale processor). The key to understanding why, is in >understanding the timing details of the interface...on a read cycle you >have to cross a clock domain back into the controller and you don't >really want 5 different answers for that timing. "so, I'll match the >DQS", (you might say), but you can't match DQS's unless you match the >source of a read DQS - which is CK and CKn.... > >jim=3D20 > >-----Original Message----- >From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] >On Behalf Of Vijay Sivasubramanian >Sent: Tuesday, May 23, 2006 7:37 AM >To: si-list@xxxxxxxxxxxxx >Subject: [SI-LIST] is clock pair-to-clock pair matching required in DDR? > >Guys -- >=3D20 > >We have designed a board with a Freescale powerQUICC processor. It has >6 separate DDR clock outputs. We have 5 DDR on-board chips. My >question is - do we have to match the length of each of the 5 >clock-pairs? I don't quite understand the need for matching the >individual clocks, but this was given in one of the Freescale app notes. >The app note recommends 20mils matching within each of the clock pairs. > > >We have matched the individual clock pair w.r.t the corresponding DQS >within 20mils and DQS to corresponding clock within 250mils. I feel as >long as the Clock-DQS-Data relationship is maintained, the clock >pair-to-pair matching might not be required. Would greatly appreciate >your help on this. > >=3D20 > >Thanks > >Vijay > >GDA Technologies Ltd., > >India > >www.gdatech.com > >=3D20 > > > >------------------------------------------------------------------ >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: =3D20 > //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 > =3D20 > >------------------------------------------------------------------ >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: =20 > //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 > =20 > >------------------------------------------------------------------ >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 > >------------------------------------------------------------------ >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 > ------------------------------------------------------------------ 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