The field of EMC engineering is evolving from the classic test-and-fix paradigm. The test lab guys will always be needed, but the new perspective recognizes that many EMI problems are symptoms of underlying SI faults best addressed at the design level rather than by slapping EMI bandaids on a black box. Really good SI practitioners have some EMC competence, and really good EMC engineers understand SI. At that level of expertise the areas blend together because it's the same physics, with the difference that SI deals with the management of milliamps inside the box while EMC deals in microamps leaking outside. The essential factor that separates the men from the boys in either area is as stated: "adequate understanding of the underlying principles" rather than "iterat(ing) empirical designs into something workable". Software is supposed to be a tool, not a crutch, and a yellow pad is for conceptual work, not "accuracy down to -50dB" (assuming that is meaningful information). Engineers who come to me waving simulation results but cannot explain what makes the plots the way they are, can be very hard to help. In any instance, I presume we are agreed that digital is just a special case of analog. The techniques and analog components necessary for high speed designs prove it. That is also why I have to disagree that "analog is analog". Opamps and LC filters are one thing. A thing of a different kind is the ability to inspect a layout to discern the hidden schematic of parasitic components that govern many EMC/SI performance issues, the ability to visualize the invisible fields that result, and the ability to gain useful information from symptoms that change simply from moving a hand or touching a surface. This is what makes EMC/SI seem like a black art to the uninitiated. If you accept that RF engineering has long been a specialty not to be taken lightly, surely the ability to design competent audio or power supply circuitry (both nontrivial tasks, based on the specification of competent as opposed to adequate) is not of itself qualification for dealing with microwave rate bit streams. Here's a thought for this forum: EMC has a recognized credential in the form of NARTE certification for those who demonstrate relevant experience and pass a qualifying exam. Is the SI field ripe for an equivalent? Should they be separate? Orin Laney P.S. Thank you, Roy, for the reference list. On Sun, 23 Mar 2008 19:30:02 -0700 "Chris Cheng" <Chris.Cheng@xxxxxxxx> writes: I walked many miles in EMI and still do. My company had never and will never have EMI only design engineers. I am responsible for anything that is not 1 and 0 in our system. I don't care if it is call SI or EMI. Analog is analog. Any engineer who work for me is capable of doing both. > As things stand today any EMI engineer can tell you that they can > make an entire > career on fixing prototype SI/EMI problems based on the same > half-dozen principles I am still waiting for you to tell me how your EMI engineer can make their career out of my examples below. From: Charlotte and/or Roy Leventhal [mailto:crleventhal@xxxxxxxxxxx] Sent: Sun 3/23/2008 8:08 PM To: Chris Cheng; olaney@xxxxxxxx; Roy.Leventhal@xxxxxxxx Cc: avtaarenator@xxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: RE: [SI-LIST] Re: Best Signal integrity Schools in the USA Chris, I'm heavily into using modeling and simulation. Check my website: http://www.semiconductorsimulation.com. I'm also a great advocate of combining EDA tools with the yellow pad for maximum efficiency and understanding. I recently had/have the opportunity to do some EMI engineering. Before either SI engineers cast aspersions on EMI engineers or vice-versa I suggest they walk in the others' moccasins a few miles. You are right that EMI engineers will have to be better tool users in the future. Why don't you help them get started, as I am trying to do? Best Regards Roy -----Original Message----- From: Chris Cheng [mailto:Chris.Cheng@xxxxxxxx] Sent: Sunday, March 23, 2008 7:52 PM To: olaney@xxxxxxxx; Roy.Leventhal@xxxxxxxx Cc: avtaarenator@xxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: RE: [SI-LIST] Re: Best Signal integrity Schools in the USA I would love to learn how to model a multi-giga bit channel with accuracy down to -50db with a yellow pad. I would love to learn how to predict eye openings of heavily loaded DDR2/3 buses with multiple loads and multiple branches and driving positions under sso and crosstalk conditions with a yellow pad. I would love to learn how to model package interconnects that has imperfect return reference planes with a yellow pad. I would love to learn how to deliver power to a multi-giga hertz IC where the power grid and via structure is inherited 2 1/2 and 3D with a yellow pad. Are you sure we are talking about the same SI work here ? What does your average EMI engineer knows about the above anyways ? From: si-list-bounce@xxxxxxxxxxxxx on behalf of olaney@xxxxxxxx Sent: Sun 3/23/2008 2:07 PM To: Roy.Leventhal@xxxxxxxx Cc: avtaarenator@xxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Best Signal integrity Schools in the USA The symptom we see today is that many designers are heavily reliant upon really big, expensive software tools to iterate empirical designs into something workable. The same designer, given adequate understanding of the underlying principles, can often do 90% of the work on a yellow pad, then use software for cleanup and as a sanity check. When I see SI related job descriptions that want work experience with a big list of tools, I can readily guess what the company mindset is: substitution of tools for competence, and bring in the consultants when they get into trouble. Orin ------------------------------------------------------------------ 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.net 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