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> æ¼ 2014/9/6 ä¸å7:45 寫éï¼ > > > > "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