Steve, Steve, Every signal will have a ground return path that passes through the closest ground pins on the neighboring PMC connectors. You will essentially create a huge open slot between the two boards that will be quite unpredictable. Crosstalk and emissions will go through the roof. Don't do this. Bad engineer, bad .... bad! scott Steve Mercer wrote: >SI-List Members, > >I have an application that requires using all 64 available pins on a PMC >connector for data signals (i.e. no local ground returns). The signals are >3.3V single-ended data lines with a rise time on the order of 1ns. The data >will be sampled at 133MHz. The connector in question will be one of a >grouping of four (in a standard PMC arrangement) and the other three >connectors have plenty of ground pins. >My question is this: What nightmares can I expect with regard to crosstalk, >ground bounce, EMI, and signal integrity in general, and how much will the >available grounds on the adjacent connectors lessen the undesirable effects? > >Regards, > >Steve Mercer, P.Eng. >SBS Technologies (Canada), Inc. >101 Randall Dr. Phone (519) 880 8228 >Waterloo ON Fax (519) 880 8118 >N2V 1C5 smercer@xxxxxxx > > >------------------------------------------------------------------ >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 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 > > > > -- Scott McMorrow Teraspeed Consulting Group LLC 2926 SE Yamhill St. Portland, OR 97214 (503) 239-5536 http://www.teraspeed.com ------------------------------------------------------------------ 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 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