hi welcome to PCB signal integrity live lessons I’m Doug Brooks president of uLTA CAD design Inc I’ve been involved in the electronics industry since age 13 that’s a long time I started my formal career in a space program back in the 60s and I’ve been involved in electronics ever since except for short detours as a professor at San Diego State and at the University of Washington I helped start ultra CAD back in 1992 we wrote some articles and then a monthly column for Pete Waddell who at that time was editor of PCB design magazine back in the early 90s at Pete’s urging I put on my first signal integrity seminar at the PCB design conference East back in 1995 that led to 17 years of seminars literally around the world and it has been a great ride prentice-hall published my first book signal integrity issues in printed circuit board design back in 2003 they published my second book ten years later in the spring of 2013 PCB currents how they flow and how they react these lessons that you’re about to watch follow the material in the second half of that book but in much more detail it may be helpful for you to have a copy of PCB currents for reference during these lessons and then afterwards after you’re through watching the lessons the lessons are organized as a series of nine primary lesson groups lesson one covers the background information that I consider to be an important foundation for signal integrity topics if you have a good background in electronics you may be tempted to skip over this I urge you please don’t I believe there are a few Nuggets for you to chew on no matter how strong your background is and I believe there are some new viewpoints here that you haven’t considered before and that’s particularly true in lesson 1.1 gaining a historical perspective and lesson 1.4 visualize electromagnetic fields lesson 1.1 discussions my view of the historical perspective of signal integrity issues on printed circuit board I believe we’ve gone through four stages that’s the way I look at it since the beginning of the circuit board stage one was trivial there were no signal integrity issues stage two started when the inductance of a trace became an issue for many of us that happened in the early 90s when we moved in to stage three we began worrying about resistance varying with frequency that got us involved with the skin effect and dielectric losses and led to the topic of lossy transmission lines in the latest stage Stage four we get into the area where frequencies and frequency harmonics are so high rise times are so short and wavelengths are so short that we can’t physically implement the solutions we developed in stages two and three even via links may be longer than the critical links we defined in stage two lessons two through seven cover the signal integrity issues related to these four stages the general outline is the same for all six lessons first we start with the nature of the problem and why it is a concern for us then we talk about the solution to the problem and then we talk about the problems we may have in implementing the solutions to the problems lessons two through five relate to stage two of the historical perspective lesson to eliminate reflections is the topic of controlled impedance traces lesson three minimize EMI and crosstalk lesson four one of my favorite topics design differential traces and lesson five solve power distribution system problems that’s the topic of bypass capacitors what size how many where to place them the role of ESR and so on lesson six gets us into stage three we talk about the skin effect and dielectric losses and that leads into the topic of lossy transmission lines and what if anything were able to do about it lesson seven gets us into stage four the problems of implementing solutions when wavelengths and critical links can be shorter than even the length of a via

and the problems that that involves then we get into lesson eight is not normally considered a signal integrity issue but it is a problem that designers often face and that is designing traces for the level of current and there’s two types of problems here first design the traces to carry a certain level of current with an acceptable increase in temperature that’s covered in lesson 8.1 design traces for temperature then the second problem is designing traces to handle a catastrophic current surge or a catastrophic current overload what we may want to do is bring down the system in a controlled manner and maybe half a second or maybe one and a half seconds to avoid damages to the system or additional systems or maybe even to nearby people less than eight point two gets into that design traces for melting point how big do we need the trace in order to survive that current surge for a short period of time and it’s really what we call a fusing question and then finally lesson nine final thoughts and it is just that it’s my opportunity to look back over the lessons and look at the topics that we’ve covered first I review again the historical trend and the historical evolution of signal integrity issues on circuit boards second I summarize the important design rules that we’ve discussed in all of the previous lessons and you might be surprised at how few there are actually when we bring them all together and talk about it third I answer the question I was asked once at the end of a seminar Doug why should we believe your design rules that’s a tough question and in that lesson I give you my answer and then finally I talk about the coming death of the printed circuit board or not thank you for taking this journey with me I sincerely hope you find this trip interesting valuable and informative

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