Hi, Steve Could you help indicate which paper in Simberian website is about vias I want to clarify my question as below # means stitching vias, * means signal vias, + means positive signal, - means negative signal 1. Only on stitching vias +++++++++++++++++*++++++++++ # --------------------------*---------------- 2. At least two stitching vias # ++++++++++++++++*+++++++++++ ------------------------*------------------ # For each structure, what is theory behind? What is your recommendation for stitching via structure in the 25Gbps structure? Thank you Lee > "steve weir" <weirsi@xxxxxxxxxx> ©ó 2014/9/6 ¤U¤È8:31 ¼g¹D¡G > > Typically, HFSS is used to design structures. > > There is not a single correct answer. Z axis transitions are not entirely > localized. One could design a D pair transition for a single pair and then > find out when they place that structure, that they have important differences > in performance due to other surrounding structures including other > transitions and stitch via patterns. Simberian has several good papers on > their web site addressing these types of issues. > > Steve >> On 9/6/2014 5:16 AM, leeyuyun wrote: >> Hi, Steve >> Thanks your information >> I have SI wave and HFSS software, and which one is better for 25Gbps >> application? >> Do you agree P/N share the same stitching via is a good way? >> Appreciate your teaching >> Regards, Lee >> >> > "steve weir" <weirsi@xxxxxxxxxx> ©ó 2014/9/6 ¤U¤È7:45 ¼g¹D¡G >> > >> > "It depends". In the general sense: Tighter stitching increases the >> > lowest cavity resonant frequencies. However stitching is not free, and >> > where stitching goes particularly close to signal vias can have a big >> > impact on how the overall structure performs. >> > >> > If you want well controlled results that meet a particular loss budget, >> > then you really need to model in a good solver. You can always contract >> > with someone to design your transitions for you. There are entire >> > businesses built around getting structures like this right: Teraspeed, >> > Wild River, etc. >> > >> > Steve >> > On 9/6/2014 4:25 AM, Leeyuyun wrote: >> > > Hi, all >> > > I am doing 100Gbps (4x25Gps) product now >> > > How do we put stitching vias when high speed signal change the layer? >> > > This is a differential pair, which has P and N >> > > Someone told me that one stitching vias is better because P and N share >> > > the common return >> > > Someone told me that more stitching vias is better because loop >> > > inductance could be reduced more >> > > I am confused which one is better? >> > > Can anyone help me? >> > > Thanks, >> > > Lee------------------------------------------------------------------ >> > > 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 >> > > >> > > >> > > >> > >> > >> > -- >> > Steve Weir >> > IPBLOX, LLC >> > 1580 Grand Point Way >> > MS 34689 >> > Reno, NV 89523-9998 >> > www.ipblox.com >> > >> > (775) 299-4236 Business >> > (866) 675-4630 Toll-free >> > (707) 780-1951 Fax >> > >> > All contents Copyright (c)2013 IPBLOX, LLC. All Rights Reserved. >> > This e-mail may contain confidential material. >> > If you are not the intended recipient, please destroy all records >> > and notify the sender. >> > >> > ------------------------------------------------------------------ >> > 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 >> > >> > >> > > > -- > Steve Weir > IPBLOX, LLC > 1580 Grand Point Way > MS 34689 > Reno, NV 89523-9998 > www.ipblox.com > > (775) 299-4236 Business > (866) 675-4630 Toll-free > (707) 780-1951 Fax > > All contents Copyright (c)2013 IPBLOX, LLC. All Rights Reserved. > This e-mail may contain confidential material. > If you are not the intended recipient, please destroy all records > and notify the sender. ------------------------------------------------------------------ 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