Shane, Why are your anticipating a difference in propagation velocity? Lee > [Original Message] > From: San Miguel, Shane <shane.san.miguel@xxxxxxxxx> > To: silist <si-list@xxxxxxxxxxxxx> > Date: 10/9/2003 3:48:54 PM > Subject: [SI-LIST] Re: Diff.Pairs > > When routing differential pairs (say clk and /clk) how does one = > accomodate the change in propagation velocity relative to the data = > signals? Do you increase the trace length (time of flight) for the data = > signals to compensate for the timing delta? > > Shane San Miguel=20 > > > > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx > [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Chris McGrath > Sent: Thursday, October 09, 2003 12:04 PM > To: silist > Subject: [SI-LIST] Re: Diff.Pairs > > > > My experience has generally been that routing the differential pairs > close together has the benefit of allowing the designer to increase > routing density and can be routed closer together than two single ended > signals. I am very interested in understanding if there are benefits of > a tightly coupled differential pair where the electromagnetic coupling > yields better SI or EMI (or other) characteristics. > > -Chris > > > > -----Original Message----- > > From: Scott McMorrow [mailto:scott@xxxxxxxxxxxxx]=3D20 > > Sent: Thursday, October 09, 2003 2:41 PM > > To: leeritchey@xxxxxxxxxxxxx; silist > > Subject: [SI-LIST] Re: Diff.Pairs > >=3D20 > >=3D20 > > Lee, > > You said about differntial pair nets: > >=3D20 > > "unless they are placed close enough together that there is some > > interaction. This interaction is not beneficial." > >=3D20 > > You have yet to prove that the coupled interaction of closely = > spaced=3D20 > > differential pairs is not beneficial. Please show the proof and = > the=3D20 > > data. Analytically, electromagnetically and observationally there = > is=3D20 > > not a problem with using close spaced differential pairs. You = > are=3D20 > > stating your opinion as an absolute fact that is not supported by=3D20 > > science. This is quite contrary to your stated belief in good=3D20 > > engineering and science. > >=3D20 > > scott > >=3D20 > >=3D20 > > Lee Ritchey wrote: > >=3D20 > > >Why do people try so hard to make the coupling between the=3D20 > > two members=3D20 > > >of a pair so important. These are two independent signals=3D20 > > that travel=3D20 > > >over planes independently unless they are placed close=3D20 > > enough together=3D20 > > >that there is some interaction. This interaction is not beneficial. > > > > > >Lee > > > > > > > > > =3D20 > > > > > >>[Original Message] > > >>From: Knighten, Jim L <JK100005@xxxxxxxxxxxxxxxx> > > >>To: <leeritchey@xxxxxxxxxxxxx>; Doug Brooks <doug@xxxxxxxxxx>; > > >> =3D20 > > >> > > ><si-list@xxxxxxxxxxxxx> > > > =3D20 > > > > > >>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=3D20 > > >>transmission lines. The mutual coupling between the traces=3D20 > > affect the=3D20 > > >>two modes that > > >> =3D20 > > >> > > >are > > > =3D20 > > > > > >>always present (even and odd modes). In the traditional=3D20 > > configuration,=3D20 > > >>the two traces are parallel and of the same width and thickness = > and=3D20 > > >>located adjacent to a plane. The degree of coupling between = > the=3D20 > > >>traces is usually described as "loosely coupled" or=3D20 > > "tightly coupled." =3D20 > > >>In either case, if > > >> =3D20 > > >> > > >the > > > =3D20 > > > > > >>signal and signal traces are perfectly differential (i.e., no=3D20 > > >>imbalance, perfectly symmetrical), then there is always=3D20 > > current in the=3D20 > > >>adjacent > > >> =3D20 > > >> > > >ground > > > =3D20 > > > > > >>plane, but the net current in the longitudinal direction (the=3D20 > > >>direction of the traces) is zero. The currents that exist in = > the=3D20 > > >>adjacent plane are circulating currents that reflect the=3D20 > > distributed=3D20 > > >>coupling between the traces down the length of the=3D20 > > transmission line. > > >> > > >>So, what if the two coupled traces are not co-planar, i.e.,=3D20 > > not in the > > >> =3D20 > > >> > > >same > > > =3D20 > > > > > >>plane? Well, you still have two coupled transmission lines, but the > > >> =3D20 > > >> > > >mutual > > > =3D20 > > > > > >>capacitance and inductance between them may be different=3D20 > > than if they=3D20 > > >>were co-planar, hence the even and odd mode impedances may be=3D20 > > >>different. These non-co-planar coupled lines can still carry=3D20 > > >>differential signals, though. > > >> =3D20 > > >> > > > > > > =3D20 > > > > > >>What if the two coupled lines were not co-planar and=3D20 > > actually had the > > >> =3D20 > > >> > > >ground > > > =3D20 > > > > > >>plane between them? This is just a special case of the = > "loosely=3D20 > > >>coupled" case, in that the lines are now not coupled at=3D20 > > all. Still,=3D20 > > >>the lines can support differential signaling, but the = > relationships=3D20 > > >>between even and odd modes are not quite the same as when they = > were=3D20 > > >>coupled. (Perhaps even mode and odd mode impedances are equal?) > > >> > > >>So, how about current in the ground plane? For perfect=3D20 > > differential=3D20 > > >>signaling, the net current in the plane is zero. When you=3D20 > > introduce=3D20 > > >>imbalance, either in the signal source, or in the signal path, = > you=3D20 > > >>create net longitudinal current in the ground plane. This=3D20 > > is the even=3D20 > > >>mode > > >> =3D20 > > >> > > >signal, > > > =3D20 > > > > > >>which has no bearing on your intended differential signal (the = > odd=3D20 > > >>mode) > > >> =3D20 > > >> > > >and > > > =3D20 > > > > > >>represents an EMI source on the ground plane. > > >> > > >>If you route differential signals on different layers, it=3D20 > > may be more=3D20 > > >>difficult to maintain balance (symmetry) in the traces than if = > the=3D20 > > >>traces were co-planar. If this is true, you have more=3D20 > > potential for=3D20 > > >>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=3D20 > > >>planes of a PCB, the return current for each member of the pair=3D20 > > >>travels on the plane over which it travels, not on the=3D20 > > other wire. If=3D20 > > >>they are very tightly coupled to each other, perhaps 5% of=3D20 > > the current=3D20 > > >>from one travels in the other. It is coincidental that the two=3D20 > > >>currents are equal in magnitude and opposite. They don't=3D20 > > have to be. =3D20 > > >>Their "return currents" still travel on the plane, not on the = > other=3D20 > > >>wire. > > >> > > >>As far as EMI is concerned, it has been demonstrated many=3D20 > > times, once=3D20 > > >>in the paper done by Doug Brooks with the staff at UMR, that = > traces=3D20 > > >>traveling over planes are not a detectable source of EMI. =3D20 > > Therefore,=3D20 > > >>constraining the routing of differential pairs to prevent them = > from=3D20 > > >>creating EMI is not appropriate or necessary. > > >> > > >>It is still true that the two members of a differential=3D20 > > pair are two=3D20 > > >>independent signals traveling on two independent=3D20 > > transmission lines.=3D20 > > >>All they have in common is that the have equal amplitudes=3D20 > > and are 180=3D20 > > >>degrees out of phase with each other. If the protocol is=3D20 > > LVDS, each=3D20 > > >>member of the pair should be parallel terminated in an=3D20 > > impedance equal=3D20 > > >>to Zo for that line to Vref (about 1.25V) which is half way = > between=3D20 > > >>the two logic levels. > > >> > > >>As long as the two signals switch at the same time, the current=3D20 > > >>flowing > > >> =3D20 > > >> > > >out > > > =3D20 > > > > > >>of Vref into one line is the same magnitude an opposite in=3D20 > > polarity to > > >> =3D20 > > >> > > >that > > > =3D20 > > > > > >>flowing into the other. The net current into and out of the = > Vref=3D20 > > >>terminal is zero, so we can omit the connection. When we=3D20 > > do this, we=3D20 > > >>have two resistors, each of value Zo across the ends of the two=3D20 > > >>transmission > > >> =3D20 > > >> > > >lines. > > > =3D20 > > > > > >>For convenience, we use one resistor of value 2 X Zo. This=3D20 > > is not a=3D20 > > >>differential impedance of 100 ohms, but two parallel=3D20 > > terminations of=3D20 > > >>value Zo terminating two transmission lines each of impedance Zo. > > >> > > >>As long as the two edges switch at the same time, there is=3D20 > > no current=3D20 > > >>imbalance and all is well. Soon as one edge switches before = > the=3D20 > > >>other, there is a need for a momentary current spike to=3D20 > > flow into or=3D20 > > >>out of the Vref terminal. If there is no connection to=3D20 > > Vref for the=3D20 > > >>current flow, > > >> =3D20 > > >> > > >the > > > =3D20 > > > > > >>result is the edges are degraded. To avoid this=3D20 > > degradation, a very=3D20 > > >>small capacitor is often connected between the two resistors = > and=3D20 > > >>ground. This > > >> =3D20 > > >> > > >is > > > =3D20 > > > > > >>a very common termination for 2.4 GB/S signal links. > > >> > > >>It is time to stop representing differential signals as=3D20 > > needing to be=3D20 > > >>tightly coupled to each other in order to operate properly. It = > is=3D20 > > >>simply not so. I have routed thousands of differential=3D20 > > signal where=3D20 > > >>each member of the pair is on a different layer. If this were = > not=3D20 > > >>possible, 1 mm > > >> =3D20 > > >> > > >pitch > > > =3D20 > > > > > >>BGAs with differential signals would be un routable. There=3D20 > > are tens=3D20 > > >>of thousands of such parts being shipped every month on PCBs = > where=3D20 > > >>they are routed apart from each other. > > >> > > >>This is all described in my recently published book, "Right=3D20 > > the First > > >> =3D20 > > >> > > >Time, > > > =3D20 > > > > > >>A Practical Handbook on High Speed PCB and System Design". =3D20 > > It is also=3D20 > > >>covered in Howard Johnson's new book whose title escapes me at the > > >> =3D20 > > >> > > >moment.. > > > =3D20 > > > > > >>Lee > > >> > > >> > > >> =3D20 > > >> > > >>>[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 > > >>> =3D20 > > >>> > > >>"loop" > > >> =3D20 > > >> > > >>>in EMI terms. That is, the loop is the area encompassed by=3D20 > > the signal > > >>> =3D20 > > >>> > > >and > > > =3D20 > > > > > >>>its return. Smaller loop areas perform better than larger=3D20 > > loop areas > > >>> =3D20 > > >>> > > >when > > > =3D20 > > > > > >>>EMI is a concern. The closer the differential pair, the smaller = > is=3D20 > > >>>the > > >>>loop. If we are NOT concerned about EMI, then this is not=3D20 > > an issue. If > > >>> =3D20 > > >>> > > >we > > > =3D20 > > > > > >>>ARE, then we might want to pay attention to this and keep the = > loop=3D20 > > >>>small > > >>> =3D20 > > >>> > > >>by > > >> =3D20 > > >> > > >>>routing the traces close together. > > >>> > > >>>The equal spacing "requirement" comes from the control of=3D20 > > reflections > > >>> =3D20 > > >>> > > >(ie > > > =3D20 > > > > > >>>transmission line termination issues.) IF we are concerned about > > >>>reflections, THEN we need a constant impedance everywhere along the > > >>> =3D20 > > >>> > > >>trace. > > >> =3D20 > > >> > > >>>IF the (differential) traces are close together (for EMI = > reasons)=3D20 > > >>>THEN > > >>> =3D20 > > >>> > > >>they > > >> =3D20 > > >> > > >>>will interact (a very special case of crosstalk, which in this > > >>> =3D20 > > >>> > > >particular > > > =3D20 > > > > > >>>case [signals --- being equal and opposite --- are exactly=3D20 > > correlated > > >>> =3D20 > > >>> > > >>with > > >> =3D20 > > >> > > >>>each other] is not a problem.) IF we want to keep a constant=3D20 > > >>>impedance > > >>>along the traces, THEN we must keep a "constant" spacing=3D20 > > between them,=3D20 > > >>>because the coupling between them, and therefore the = > differential=3D20 > > >>>impedance, will vary if we don't. > > >>> > > >>>There is a further design rule you sometimes hear, that being = > that=3D20 > > >>>the > > >>>differential traces must be equal length. This is NOT for timing > > >>> =3D20 > > >>> > > >reasons, > > > =3D20 > > > > > >>>but for common mode reasons. A strong assumption we make about > > >>> =3D20 > > >>> > > >>differential > > >> =3D20 > > >> > > >>>signals is that they are equal and opposite, and therefore=3D20 > > there is=3D20 > > >>>no > > >>>return signal through the ground system. Even if the signals are > > >>> =3D20 > > >>> > > >perfect, > > > =3D20 > > > > > >>>if the traces are different length, then the signal will=3D20 > > not arrive=3D20 > > >>>at > > >>> =3D20 > > >>> > > >>the > > >> =3D20 > > >> > > >>>far end at exactly the same time and the signals will not=3D20 > > be "equal=3D20 > > >>>and > > >>>opposite" at the receiver. Just a couple of degrees phase=3D20 > > shift can make > > >>> =3D20 > > >>> > > >>a > > >> =3D20 > > >> > > >>>surprising difference between the signals when we are talking about > > >>>(square-wave) clock signals. If the signals are not=3D20 > > exactly equal and=3D20 > > >>>opposite, then there MUST be a net current flowing=3D20 > > somewhere else. This=3D20 > > >>>will quite likely be a common mode noise current that=3D20 > > might cause an EMI > > >>> =3D20 > > >>> > > >>issue. > > >> =3D20 > > >> > > >>>None of the differential signal trace design rules are = > necessary=3D20 > > >>>taken > > >>> =3D20 > > >>> > > >by > > > =3D20 > > > > > >>>themselves. This is important to recognize. But if are = > concerned=3D20 > > >>>about > > >>>certain SI issues, they might lead to some design=3D20 > > considerations which > > >>> =3D20 > > >>> > > >>THEN > > >> =3D20 > > >> > > >>>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: > > >>> =3D20 > > >>> > > >>>>More than that, it does not have any benefit. Tight coupling = > of=3D20 > > >>>>differential pairs forces the traces to be narrower=3D20 > > increasing the=3D20 > > >>>>skin effect losses. Also, this tight coupling is going=3D20 > > to result in=3D20 > > >>>>good > > >>>> =3D20 > > >>>> > > >old > > > =3D20 > > > > > >>>>cross talk that actually degrades the edges. > > >>>> > > >>>>How the notion of tight coupling of differential pairs as=3D20 > > beneficial > > >>>> =3D20 > > >>>> > > >got > > > =3D20 > > > > > >>>>started is a mystery to me. There are several references=3D20 > > that show > > >>>> =3D20 > > >>>> > > >that > > > =3D20 > > > > > >>>>tight coupling is not beneficial, one of them is Howard Johnson's > > >>>> =3D20 > > >>>> > > >latest > > > =3D20 > > > > > >>>>book, at least one column he has written and my recently = > released=3D20 > > >>>>book. > > >>>> > > >>>>Lee Ritchey > > >>>> > > >>>> > > >>>> =3D20 > > >>>> > > >>>>>[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 > > >>>>> =3D20 > > >>>>> > > >>expensive. > > >> =3D20 > > >> > > >>>>> You can do this, but it drives up the cost of the board. > > >>>>> > > >>>>>Duane > > >>>>> > > >>>>> =3D20 > > >>>>> > > >>>>>>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 > > >>>>>> =3D20 > > >>>>>> > > >when > > > =3D20 > > > > > >>>>>>using woven glass reinforced=3D20 > > >>>>>><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=3D20 > > >>>>>><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 > > >>>>>> > > =3D > >>>>>>=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= > 3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D > =3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= > 3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D > > >>>>>> Controlled Impedance & Signal integrity tools > > >>>>>> for the Printed circuit fabrication industry=3D20 > > =3D > >>>>>>=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= > 3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D > =3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= > 3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>>At 19:00 02/10/2003, you wrote: > > >>>>>> > > >>>>>> =3D20 > > >>>>>> > > >>>>>>>I am seeking help in finding enlightenment regarding=3D20 > > electrical=3D20 > > >>>>>>>performance pros and cons and how manufacturing=3D20 > > tolerances play a > > >>>>>>> =3D20 > > >>>>>>> > > >>role > > >> =3D20 > > >> > > >>>>>>>when comparing side by side and tandem differential pairs. I'd > > >>>>>>> =3D20 > > >>>>>>> > > >>>>appreciate > > >>>> =3D20 > > >>>> > > >>>>>>>your opinion, experience, analysis, pointers to papers and > > >>>>>>> =3D20 > > >>>>>>> > > >articels, > > > =3D20 > > > > > >>>>etc. > > >>>> =3D20 > > >>>> > > >>>>>>>In return, I would offer to share a summary of the > > >>>>>>> =3D20 > > >>>>>>> > > >>finding/discoveries > > >> =3D20 > > >> > > >>>>>>>with interested parties. > > >>>>>>> > > >>>>>>>Thanks > > >>>>>>> > > >>>>>>>Juergen > > >>>>>>> > > >>>>>>> > > >>>>>>> > > >>>>>>>------------------------------------------------------- > > ---------- > > >>>>>>>- > > >>>>>>>To unsubscribe from si-list: > > >>>>>>>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject > > >>>>>>> =3D20 > > >>>>>>> > > >>field > > >> =3D20 > > >> > > >>>>>>>or to administer your membership from a web page, go to:=3D20 > > >>>>>>>//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 > > >>>>>>> > > >>>>>>> =3D20 > > >>>>>>> > > >>>>>> > > >>>>>>-------------------------------------------------------- > > ---------- > > >>>>>>To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx = > with=3D20 > > >>>>>>'unsubscribe' in the Subject > > >>>>>> =3D20 > > >>>>>> > > >>field > > >> =3D20 > > >> > > >>>>>>or to administer your membership from a web page, go to:=3D20 > > >>>>>>//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 > > >>>>>> > > >>>>>> =3D20 > > >>>>>> > > >>>>>-- > > >>>>>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 > > >>>>> =3D20 > > >>>>> > > >field > > > =3D20 > > > > > >>>>>or to administer your membership from a web page, go to:=3D20 > > >>>>>//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 > > >>>>> > > >>>>> =3D20 > > >>>>> > > >>>> > > >>>>------------------------------------------------------------------ > > >>>>To unsubscribe from si-list: > > >>>>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the = > Subject=3D20 > > >>>>field > > >>>> > > >>>>or to administer your membership from a web page, go to:=3D20 > > >>>>//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 > > >>>> > > >>>> =3D20 > > >>>> > > >>>Doug Brooks' new book, "Signal Integrity Issues and Printed Circuit > > >>> =3D20 > > >>> > > >Board > > > =3D20 > > > > > >>>Design" has just been released by Prentice Hall. See details and > > >>> =3D20 > > >>> > > >ordering > > > =3D20 > > > > > >>>info at www.ultracad.com > > >>> > > >>> =3D20 > > >>> > > >_____________________________________________________________ > > __________ > > >_____ > > > =3D20 > > > > > >>__ > > >> =3D20 > > >> > > >>>------------------------------------------------------------------ > > >>>To unsubscribe from si-list: > > >>>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the=3D20 > > Subject field > > >>> > > >>>or to administer your membership from a web page, go to:=3D20 > > >>>//www.freelists.org/webpage/si-list > > >>> > > >>>For help: > > >>>si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > >>> > > >>>List archives are viewable at: =3D20 > > >>> //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 > > >>> =3D20 > > >>> =3D20 > > >>> > > >> > > >>------------------------------------------------------------------ > > >>To unsubscribe from si-list: > > >>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the=3D20 > > Subject field > > >> > > >>or to administer your membership from a web page, go to:=3D20 > > >>//www.freelists.org/webpage/si-list > > >> > > >>For help: > > >>si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > >> > > >>List archives are viewable at: =3D20 > > >> //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 > > >> =3D20 > > >> =3D20 > > >> > > > > > > > > > > > >------------------------------------------------------------------ > > >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:=3D20 > > >//www.freelists.org/webpage/si-list > > > > > >For help: > > >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > > > >List archives are viewable at: =3D20 > > > //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 > > > =3D20 > > > > > > =3D20 > > > > >=3D20 > > --=3D20 > > Scott McMorrow > > Teraspeed Consulting Group LLC > > 2926 SE Yamhill St. > > Portland, OR 97214 > > (503) 239-5536 > > http://www.teraspeed.com > >=3D20 > >=3D20 > >=3D20 > >=3D20 > > ------------------------------------------------------------------ > > To unsubscribe from si-list: > > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > >=3D20 > > or to administer your membership from a web page, go to:=3D20 > > //www.freelists.org/webpage/si-list > >=3D20 > > For help: > >=3D20 > > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >=3D20 > > List archives are viewable at: =3D20 > > //www.freelists.org/archives/si-list > > or at our remote archives: > > http://groups.yahoo.com/group/si-list/messages=3D20 > > Old (prior to June 6, 2001) list archives are viewable at: > > http://www.qsl.net/wb6tpu > > =3D20 > >=3D20 > ------------------------------------------------------------------ > 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: =20 > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages=20 > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > =20 > > ------------------------------------------------------------------ > 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