Low frequency: lumped capacitance, inductance, resistance. High frequency: Wave modes. Steve On 9/8/2014 12:35 AM, Leeyuyun wrote: > Hi, Steve > Could you help explain >> I think that you are considering a high frequency problem in low >> frequency terms > I do not understand "in low frequency terms", could you help clarify it? > How to roughly evaluate cavity effect when stitching via close to > signal vias? > Any white paper or material to show stitching via effect? > When I ask two parties to run two kinds of simulation, including only > one stitching vias and more stitching vias, the result from two > parties is different. One shows only one stitching is better, but > another shows more stitching vias better. How do I make decision which > one is correct? > Thank you > Lee > > > steve weir <weirsi@xxxxxxxxxx <mailto:weirsi@xxxxxxxxxx>> æ¼ 2014/9/8 > ä¸å11:57 寫éï¼ > >> It is neither. It is a description of the physics. Real engineering >> accounts for pertinent physics. >> >> Best Regards, >> >> >> Steve >> On 9/7/2014 6:41 PM, leeritchey@xxxxxxxxxxxxx wrote: >>> This sounds like a bit of supposiition rather than real engineering. >>> >>> Sent from my HTC One⢠X, an AT&T 4G LTE smartphone >>> >>> ----- Reply message ----- >>> From: "steve weir" <weirsi@xxxxxxxxxx> >>> To: "Leeyuyun" <lee.home.61@xxxxxxxxx> >>> Cc: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx> >>> Subject: [SI-LIST] Re: One stitching via or more vias is better for >>> 25Gbps application??? >>> Date: Sun, Sep 7, 2014 10:43 AM >>> >>> >>> I think that you are considering a high frequency problem in low >>> frequency terms. Stitch vias impact the cavity, and when they are in >>> close proximity to signal vias and traces, they affect wave modes near >>> those structures. Thinking about stitch vias and the cavities that >>> they >>> traverse as though they are continuations of the TEM path that >>> breaks at >>> a Z axis transition is not a good approximation. The Z axis signal >>> transition injects the signal energy into the cavity. The various >>> properties of the cavity: material, and geometry, including what vias >>> stitch the cavity surfaces together and where affects how that signal >>> energy propagates through the cavity in all directions. >>> >>> Steve >>> On 9/7/2014 5:31 AM, Leeyuyun wrote: >>> > Hi, Steve >>> > But IL and RL should depend upon the distance / via pad size of >>> signal via and gnd stitching via >>> > If only depend on capacitor vsd via, is the return path loop >>> larger to create large inductance? >>> > Does it fit into 25Gbps application? >>> > Could you advise what is the benefit of case 1 and case 2? >>> > Thanks >>> > Lee >>> > >>> > >>> >> steve weir <weirsi@xxxxxxxxxx> æ¼ 2014/9/7 ä¸å6:11 寫éï¼ >>> >> >>> >> The statement is based on the idea that Vss stitching from bypass >>> >> capacitor Vss vias and IC Vss vias is adequate. The idea >>> concludes that >>> >> explicit vias corresponding to signal or signal pair transitions >>> are not >>> >> necessary. >>> >> >>> >> Steve >>> >>> On 9/7/2014 2:46 AM, Leeyuyun wrote: >>> >>> Stitching should be needed when gnd reference plane change >>> >>> I do not know why you said do not need any stitching 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? >>> >>> >>> >>>> "Lee " <leeritchey@xxxxxxxxxxxxx> æ¼ 2014/9/7 ä¸å3:17 寫éï¼ >>> >>>> >>> >>>> No stitching vias are needed. Where did this idea get started? >>> >>>> >>> >>>> -----Original Message----- From: Leeyuyun >>> >>>> Sent: Saturday, September 06, 2014 4:25 AM >>> >>>> To: si-list@xxxxxxxxxxxxx >>> >>>> Cc: lee.home.61@xxxxxxxxx >>> >>>> Subject: [SI-LIST] One stitching via or more vias is better for >>> 25Gbps application??? >>> >>>> >>> >>>> 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 >>> >>>> >>> >>>> >>> >>>> >>> >>>> >>> >>>> ----- >>> >>>> No virus found in this message. >>> >>>> Checked by AVG - www.avg.com >>> >>>> Version: 2014.0.4765 / Virus Database: 4015/8162 - Release >>> Date: 09/05/14 >>> >>> ------------------------------------------------------------------ >>> >>> 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 >>> >>> >> >> >> -- >> 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. -- 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