Hi Duane, So how does one determine if it is magnetic or capacitive crosstalk that is dominating in a particular configuration? Let's say I get two matrices from a field solver that look like this: C11 C12 C21 C22 and L11 L12 L21 L22 Do I just look at how C12/C11 compares to L12/L11 and how C21/C22 compares to L21/L22 ? Thanks Damon > X-Original-To: si-list@xxxxxxxxxxxxx > Delivered-To: si-list@xxxxxxxxxxxxx > From: Duane Takahashi > <duanet@xxxxxxxxxxxxxxxxxxxxxx> > User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; > en-US; rv:1.4) > Gecko/20030624 Netscape/7.1 (ax) > X-Accept-Language: en-us, en > MIME-Version: 1.0 > To: si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: Guard traces for differential > pairs > Content-Transfer-Encoding: 8bit > X-archive-position: 8392 > X-ecartis-version: Ecartis v1.0.0 > X-original-sender: duanet@xxxxxxxxxxxxxxxxxxxxxx > X-list: si-list > > It also depends on the type of crosstalk: electric > or magnetic ( > capacitive or inductive ). If it's magnetic, guard > traces won't help. > If it's capacitive, guards will help but will leave > you with the > 'magnetic remainder' of the xtalk. > > I've seen high impedance lines, more than 60 ohms, > exhibit inductive > xtalk. My guess is guard traces would not have > helped in this case. > > Regards, > Duane > > > Sogo, > > > > It is true that guard traces can INCREASE > crosstalk, but > > this can be avoided (and crosstalk in fact can be > REDUCED) > > if the via stitching is frequent enough. Between > each > > stitching, there is a half-wavelength resonator, > with a > > lowest resonance frequency of fres=1/(2*tpd), > where > > tpd is the propagation delay between two stitching > vias. > > As long as the bandwidth of the signal on the > structure > > is safely below this resonance frequency, there > should be no > > problem with signal integrity. > > > > Regards, > > > > Istvan Novak > > SUN Microsystems __________________________________ Do you Yahoo!? The New Yahoo! Shopping - with improved product search http://shopping.yahoo.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 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