Lee, I agree that the signal is degraded due to reduced conductor width. However, i respectfully disagree regarding coupling. Only the even mode components are degraded, not the odd mode. And again, I say that the degradation is only on the order of 20%. If you need to push the length limits of your traces, then by all means, weakly coupled differential pairs are in order. But it is a very, very bad idea to place them on different signal layers. you will cause additional skew due to Er variations, especially if the two stripline layers are build with different laminates. For example, in many large boards, one stripline layer might be built with prepreg surrounding core, an on another with core surrounding prepreg. These two layers will often have a different epoxy/glass ratio and will therefore have different Er and propogation velocities. In addition, routing on different layers will cause the propagation path through vias to be different. If someone were to route a differential pair on the top and bottom stripline layers on an .100" board, you will see a skew difference betwen 20 and 30 ps, depending upon the via, pad and antipad sizes, not to mention some of the different parallel plate model effects you will see due to these different transitions. These will cause strong differential to common mode converstion problems ... and, if there is a point in the system where common mode can radiate, such as a poorly designed package, poorly shield connector pin field or cable, then it will radiate and you will see a noticable increase in EMI. I agree with you that one can utilize large uncoupled differential traces effectively in boards. I do it all the time myself. I also agree that there is additional loss due to narrow closely spaced differential traces. With these losses comes an engineering tradeoff of routing density vs loss. Sometimes losses win. Sometimes density wins. And sometimes it is just a tossup. I disagree in the additional coupling effects that you believe occur, and suspect that they are due to mismatches in the system at via or connector transitions. These issues can be dealt with with good engineering. If you have data that contridicts this, I will happy to refine my opinion. I too have pushed the limits, but in my case it has been 3.125, and 10 Gbps and 20 GHz systems, at the backplane, line card, connector and packaging level. I've designed extremely low insertion loss 10 Gbps packages, SMA transitions with 30 GHz bandwidth, and some pretty nifty transitions from strongly coupled differential pairs to weakly coupled connector pin fields. I routinely use a time domain full wave field solver to design some of the more interesting structures in systems, and have correlated it to measurements. And have validated our measurement environment out to 20 GHz. I also find that additional conductor losses can have a beneficial affect on overall broadband performance, by reducing the Q of resonant circuits that are formed between the natural impedance discontinuities that form within a system. best regards, scott -- Scott McMorrow Teraspeed Consulting Group LLC 2926 SE Yamhill St. Portland, OR 97214 (503) 239-5536 http://www.teraspeed.com Lee Ritchey wrote: > Scott, > > Both I and Howard Johnson have shown this. The first degradation > comes from the need to narrow the traces in order to maintain the 50 > ohm impedance of each line. The degradation comes from increased skin > effect loss. > > The second degradation comes from the coupling which needs to be shown > with a full path analysis. I'll be showing this in my next book. > > Lee > > > > ----- Original Message ----- > From: Vinu Arumugham <mailto:vinu@xxxxxxxxx> > To: scott@xxxxxxxxxxxxx <mailto:scott@xxxxxxxxxxxxx> > Cc: leeritchey@xxxxxxxxxxxxx <mailto:leeritchey@xxxxxxxxxxxxx> > Sent: 10/9/2003 6:12:10 PM > Subject: Re: [SI-LIST] Re: Diff.Pairs > > Scott McMorrow wrote: > >>Lee, >>You said about differntial pair nets: >> >> "unless they are placed close enough together that there is some >> interaction. This interaction is not beneficial." >> >> > Scott, at least for signal degradation due to the proximity > effect, would this statement not be true? > >>You have yet to prove that the coupled interaction of closely spaced >>differential pairs is not beneficial. Please show the proof and the >>data. Analytically, electromagnetically and observationally there is >>not a problem with using close spaced differential pairs. You are >>stating your opinion as an absolute fact that is not supported by >>science. This is quite contrary to your stated belief in good >>engineering and science. >> >>scott >> >> >>Lee Ritchey wrote: >> >> >> >>>Why do people try so hard to make the coupling between the two members of a >>>pair so important. These are two independent signals that travel over >>>planes independently unless they are placed close enough together that >>>there is some interaction. This interaction is not beneficial. >>> >>>Lee >>> >>> >>> >>> >>> >>> >>>>[Original Message] >>>>From: Knighten, Jim L <JK100005@xxxxxxxxxxxxxxxx> >>>>To: <leeritchey@xxxxxxxxxxxxx>; Doug Brooks <doug@xxxxxxxxxx>; >>>> >>>> >>>> >>>> >>><si-list@xxxxxxxxxxxxx> >>> >>> >>> >>> >>>>Date: 10/9/2003 10:40:29 AM >>>>Subject: RE: [SI-LIST] Re: Diff.Pairs >>>> >>>>Lee, >>>> >>>>Your post is interesting! >>>> >>>>Differential signaling is usually implemented with coupled transmission >>>>lines. The mutual coupling between the traces affect the two modes that >>>> >>>> >>>> >>>> >>>are >>> >>> >>> >>> >>>>always present (even and odd modes). In the traditional configuration, the >>>>two traces are parallel and of the same width and thickness and located >>>>adjacent to a plane. The degree of coupling between the traces is usually >>>>described as "loosely coupled" or "tightly coupled." In either case, if >>>> >>>> >>>> >>>> >>>the >>> >>> >>> >>> >>>>signal and signal traces are perfectly differential (i.e., no imbalance, >>>>perfectly symmetrical), then there is always current in the adjacent >>>> >>>> >>>> >>>> >>>ground >>> >>> >>> >>> >>>>plane, but the net current in the longitudinal direction (the direction of >>>>the traces) is zero. The currents that exist in the adjacent plane are >>>>circulating currents that reflect the distributed coupling between the >>>>traces down the length of the transmission line. >>>> >>>>So, what if the two coupled traces are not co-planar, i.e., not in the >>>> >>>> >>>> >>>> >>>same >>> >>> >>> >>> >>>>plane? Well, you still have two coupled transmission lines, but the >>>> >>>> >>>> >>>> >>>mutual >>> >>> >>> >>> >>>>capacitance and inductance between them may be different than if they were >>>>co-planar, hence the even and odd mode impedances may be different. These >>>>non-co-planar coupled lines can still carry differential signals, though. >>>> >>>> >>>> >>>> >>> >>> >>> >>> >>>>What if the two coupled lines were not co-planar and actually had the >>>> >>>> >>>> >>>> >>>ground >>> >>> >>> >>> >>>>plane between them? This is just a special case of the "loosely coupled" >>>>case, in that the lines are now not coupled at all. Still, the lines can >>>>support differential signaling, but the relationships between even and odd >>>>modes are not quite the same as when they were coupled. (Perhaps even mode >>>>and odd mode impedances are equal?) >>>> >>>>So, how about current in the ground plane? For perfect differential >>>>signaling, the net current in the plane is zero. When you introduce >>>>imbalance, either in the signal source, or in the signal path, you create >>>>net longitudinal current in the ground plane. This is the even mode >>>> >>>> >>>> >>>> >>>signal, >>> >>> >>> >>> >>>>which has no bearing on your intended differential signal (the odd mode) >>>> >>>> >>>> >>>> >>>and >>> >>> >>> >>> >>>>represents an EMI source on the ground plane. >>>> >>>>If you route differential signals on different layers, it may be more >>>>difficult to maintain balance (symmetry) in the traces than if the traces >>>>were co-planar. If this is true, you have more potential for EMI issues. >>>> >>>>...My thoughts >>>> >>>>Jim >>>> >>>>________________________ >>>>James L. Knighten, Ph.D. >>>>Teradata, a division of NCR http://www.ncr.com >>>>17095 Via del Campo >>>>San Diego, CA 92127 >>>>tel: 858-485-2537 >>>>fax: 858-485-3788 >>>> >>>> >>>>-----Original Message----- >>>>From: Lee Ritchey [mailto:leeritchey@xxxxxxxxxxxxx] >>>>Sent: Thursday, October 09, 2003 9:30 AM >>>>To: Doug Brooks; si-list@xxxxxxxxxxxxx >>>>Subject: [SI-LIST] Re: Diff.Pairs >>>> >>>>If this discussion is about differential pairs travelling over the planes >>>>of a PCB, the return current for each member of the pair travels on the >>>>plane over which it travels, not on the other wire. If they are very >>>>tightly coupled to each other, perhaps 5% of the current from one travels >>>>in the other. It is coincidental that the two currents are equal in >>>>magnitude and opposite. They don't have to be. Their "return currents" >>>>still travel on the plane, not on the other wire. >>>> >>>>As far as EMI is concerned, it has been demonstrated many times, once in >>>>the paper done by Doug Brooks with the staff at UMR, that traces traveling >>>>over planes are not a detectable source of EMI. Therefore, constraining >>>>the routing of differential pairs to prevent them from creating EMI is not >>>>appropriate or necessary. >>>> >>>>It is still true that the two members of a differential pair are two >>>>independent signals traveling on two independent transmission lines. All >>>>they have in common is that the have equal amplitudes and are 180 degrees >>>>out of phase with each other. If the protocol is LVDS, each member of the >>>>pair should be parallel terminated in an impedance equal to Zo for that >>>>line to Vref (about 1.25V) which is half way between the two logic levels. >>>> >>>>As long as the two signals switch at the same time, the current flowing >>>> >>>> >>>> >>>> >>>out >>> >>> >>> >>> >>>>of Vref into one line is the same magnitude an opposite in polarity to >>>> >>>> >>>> >>>> >>>that >>> >>> >>> >>> >>>>flowing into the other. The net current into and out of the Vref terminal >>>>is zero, so we can omit the connection. When we do this, we have two >>>>resistors, each of value Zo across the ends of the two transmission >>>> >>>> >>>> >>>> >>>lines. >>> >>> >>> >>> >>>>For convenience, we use one resistor of value 2 X Zo. This is not a >>>>differential impedance of 100 ohms, but two parallel terminations of value >>>>Zo terminating two transmission lines each of impedance Zo. >>>> >>>>As long as the two edges switch at the same time, there is no current >>>>imbalance and all is well. Soon as one edge switches before the other, >>>>there is a need for a momentary current spike to flow into or out of the >>>>Vref terminal. If there is no connection to Vref for the current flow, >>>> >>>> >>>> >>>> >>>the >>> >>> >>> >>> >>>>result is the edges are degraded. To avoid this degradation, a very small >>>>capacitor is often connected between the two resistors and ground. This >>>> >>>> >>>> >>>> >>>is >>> >>> >>> >>> >>>>a very common termination for 2.4 GB/S signal links. >>>> >>>>It is time to stop representing differential signals as needing to be >>>>tightly coupled to each other in order to operate properly. It is simply >>>>not so. I have routed thousands of differential signal where each member >>>>of the pair is on a different layer. If this were not possible, 1 mm >>>> >>>> >>>> >>>> >>>pitch >>> >>> >>> >>> >>>>BGAs with differential signals would be un routable. There are tens of >>>>thousands of such parts being shipped every month on PCBs where they are >>>>routed apart from each other. >>>> >>>>This is all described in my recently published book, "Right the First >>>> >>>> >>>> >>>> >>>Time, >>> >>> >>> >>> >>>>A Practical Handbook on High Speed PCB and System Design". It is also >>>>covered in Howard Johnson's new book whose title escapes me at the >>>> >>>> >>>> >>>> >>>moment.. >>> >>> >>> >>> >>>>Lee >>>> >>>> >>>> >>>> >>>> >>>> >>>>>[Original Message] >>>>>From: Doug Brooks <doug@xxxxxxxxxx> >>>>>To: <si-list@xxxxxxxxxxxxx> >>>>>Date: 10/3/2003 1:02:25 PM >>>>>Subject: [SI-LIST] Re: Diff.Pairs >>>>> >>>>>Tight may be a relative word. But a differential pair constitutes a >>>>> >>>>> >>>>> >>>>> >>>>"loop" >>>> >>>> >>>> >>>> >>>>>in EMI terms. That is, the loop is the area encompassed by the signal >>>>> >>>>> >>>>> >>>>> >>>and >>> >>> >>> >>> >>>>>its return. Smaller loop areas perform better than larger loop areas >>>>> >>>>> >>>>> >>>>> >>>when >>> >>> >>> >>> >>>>>EMI is a concern. The closer the differential pair, the smaller is the >>>>>loop. If we are NOT concerned about EMI, then this is not an issue. If >>>>> >>>>> >>>>> >>>>> >>>we >>> >>> >>> >>> >>>>>ARE, then we might want to pay attention to this and keep the loop small >>>>> >>>>> >>>>> >>>>> >>>>by >>>> >>>> >>>> >>>> >>>>>routing the traces close together. >>>>> >>>>>The equal spacing "requirement" comes from the control of reflections >>>>> >>>>> >>>>> >>>>> >>>(ie >>> >>> >>> >>> >>>>>transmission line termination issues.) IF we are concerned about >>>>>reflections, THEN we need a constant impedance everywhere along the >>>>> >>>>> >>>>> >>>>> >>>>trace. >>>> >>>> >>>> >>>> >>>>>IF the (differential) traces are close together (for EMI reasons) THEN >>>>> >>>>> >>>>> >>>>> >>>>they >>>> >>>> >>>> >>>> >>>>>will interact (a very special case of crosstalk, which in this >>>>> >>>>> >>>>> >>>>> >>>particular >>> >>> >>> >>> >>>>>case [signals --- being equal and opposite --- are exactly correlated >>>>> >>>>> >>>>> >>>>> >>>>with >>>> >>>> >>>> >>>> >>>>>each other] is not a problem.) IF we want to keep a constant impedance >>>>>along the traces, THEN we must keep a "constant" spacing between them, >>>>>because the coupling between them, and therefore the differential >>>>>impedance, will vary if we don't. >>>>> >>>>>There is a further design rule you sometimes hear, that being that the >>>>>differential traces must be equal length. This is NOT for timing >>>>> >>>>> >>>>> >>>>> >>>reasons, >>> >>> >>> >>> >>>>>but for common mode reasons. A strong assumption we make about >>>>> >>>>> >>>>> >>>>> >>>>differential >>>> >>>> >>>> >>>> >>>>>signals is that they are equal and opposite, and therefore there is no >>>>>return signal through the ground system. Even if the signals are >>>>> >>>>> >>>>> >>>>> >>>perfect, >>> >>> >>> >>> >>>>>if the traces are different length, then the signal will not arrive at >>>>> >>>>> >>>>> >>>>> >>>>the >>>> >>>> >>>> >>>> >>>>>far end at exactly the same time and the signals will not be "equal and >>>>>opposite" at the receiver. Just a couple of degrees phase shift can make >>>>> >>>>> >>>>> >>>>> >>>>a >>>> >>>> >>>> >>>> >>>>>surprising difference between the signals when we are talking about >>>>>(square-wave) clock signals. If the signals are not exactly equal and >>>>>opposite, then there MUST be a net current flowing somewhere else. This >>>>>will quite likely be a common mode noise current that might cause an EMI >>>>> >>>>> >>>>> >>>>> >>>>issue. >>>> >>>> >>>> >>>> >>>>>None of the differential signal trace design rules are necessary taken >>>>> >>>>> >>>>> >>>>> >>>by >>> >>> >>> >>> >>>>>themselves. This is important to recognize. But if are concerned about >>>>>certain SI issues, they might lead to some design considerations which >>>>> >>>>> >>>>> >>>>> >>>>THEN >>>> >>>> >>>> >>>> >>>>>might cascade (like a domino effect) into other areas. >>>>> >>>>>This is in my book, too............... >>>>> >>>>>Doug Brooks >>>>> >>>>> >>>>> >>>>> >>>>>At 11:41 AM 10/3/2003 -0700, Lee Ritchey wrote: >>>>> >>>>> >>>>> >>>>> >>>>>>More than that, it does not have any benefit. Tight coupling of >>>>>>differential pairs forces the traces to be narrower increasing the skin >>>>>>effect losses. Also, this tight coupling is going to result in good >>>>>> >>>>>> >>>>>> >>>>>> >>>old >>> >>> >>> >>> >>>>>>cross talk that actually degrades the edges. >>>>>> >>>>>>How the notion of tight coupling of differential pairs as beneficial >>>>>> >>>>>> >>>>>> >>>>>> >>>got >>> >>> >>> >>> >>>>>>started is a mystery to me. There are several references that show >>>>>> >>>>>> >>>>>> >>>>>> >>>that >>> >>> >>> >>> >>>>>>tight coupling is not beneficial, one of them is Howard Johnson's >>>>>> >>>>>> >>>>>> >>>>>> >>>latest >>> >>> >>> >>> >>>>>>book, at least one column he has written and my recently released book. >>>>>> >>>>>>Lee Ritchey >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>[Original Message] >>>>>>>From: Duane Takahashi <duanet@xxxxxxxxxxxxxxxxxxxxxx> >>>>>>>To: <si-list@xxxxxxxxxxxxx> >>>>>>>Date: 10/2/2003 3:58:59 PM >>>>>>>Subject: [SI-LIST] Re: Diff.Pairs >>>>>>> >>>>>>>Hi Juergen: >>>>>>> >>>>>>>Aligning the stack up for the broadside coupled diff lines is >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>expensive. >>>> >>>> >>>> >>>> >>>>>>> You can do this, but it drives up the cost of the board. >>>>>>> >>>>>>>Duane >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>>>Hi Juergen, >>>>>>>>You can find lots of application notes >>>>>>>>especially with respect to process variation >>>>>>>>on differential pairs here: >>>>>>>> >>>>>>>> >>>>>>>>www.polarinstruments.com/support/cits/cits_index.html >>>>>>>> >>>>>>>>In particular this one may be of interest: >>>>>>>> >>>>>>>> >>>>>>>>How measured impedance may vary from field solver calculations >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>when >>> >>> >>> >>> >>>>>>>>using woven glass reinforced >>>>>>>><http://www.polarinstruments.com/support/cits/AP139.html>laminates >>>>>>>> >>>>>>>>www.polarinstruments.com/support/cits/AP139.html >>>>>>>> >>>>>>>> >>>>>>>>And this note: >>>>>>>> >>>>>>>>Copper thickness, edge coupled lines and >>>>>>>>characteristic >>>>>>>><http://www.polarinstruments.com/support/cits/AP151.html>impedance >>>>>>>> >>>>>>>> >>>>>>>>www.polarinstruments.com/support/cits/AP151.html >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>Hope this helps.... >>>>>>>> >>>>>>>> >>>>>>>>Kind regards >>>>>>>>Martyn Gaudion >>>>>>>>www.polarinstruments.com >>>>>>>>T: +44 1481 253081 >>>>>>>>F: +44 1481 252476 >>>>>>>>M: +44 7710 522748 >>>>>>>>E: martyn@xxxxxxxxxxxxxxxxxxxx >>>>>>>> >>>>>>>>============================================ >>>>>>>> Controlled Impedance & Signal integrity tools >>>>>>>> for the Printed circuit fabrication industry >>>>>>>>============================================ >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>At 19:00 02/10/2003, you wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>>I am seeking help in finding enlightenment regarding electrical >>>>>>>>>performance pros and cons and how manufacturing tolerances play a >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>role >>>> >>>> >>>> >>>> >>>>>>>>>when comparing side by side and tandem differential pairs. I'd >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>appreciate >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>>>your opinion, experience, analysis, pointers to papers and >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>articels, >>> >>> >>> >>> >>>>>>etc. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>>>In return, I would offer to share a summary of the >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>finding/discoveries >>>> >>>> >>>> >>>> >>>>>>>>>with interested parties. >>>>>>>>> >>>>>>>>>Thanks >>>>>>>>> >>>>>>>>>Juergen >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>>------------------------------------------------------------------ >>>>>>>>>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 >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>------------------------------------------------------------------ >>>>>>>>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 >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>-- >>>>>>>Duane Takahashi phone: 408-720-4200 >>>>>>>Greenfield Networks fax: 408-720-4210 >>>>>>>255 Santa Ana Court email: duanet@xxxxxxxxxxxxxxxxxxxxxx >>>>>>>Sunnyvale, CA 94085 >>>>>>> >>>>>>>* MOVING! Please note new numbers and address * >>>>>>> >>>>>>>------------------------------------------------------------------ >>>>>>>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 >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>------------------------------------------------------------------ >>>>>>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 >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>Doug Brooks' new book, "Signal Integrity Issues and Printed Circuit >>>>> >>>>> >>>>> >>>>> >>>Board >>> >>> >>> >>> >>>>>Design" has just been released by Prentice Hall. See details and >>>>> >>>>> >>>>> >>>>> >>>ordering >>> >>> >>> >>> >>>>>info at www.ultracad.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 >>>>> >>>>> >>>>> >>>>> >>>>> >>>>------------------------------------------------------------------ >>>>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 >>>> >>>> >>>> >>>> >>>> >>>------------------------------------------------------------------ >>>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 >>> >>> >>> >>> >>> >>> >> >> >> > ------------------------------------------------------------------ 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