Book Review

Title: PCB Design for Real-World EMI Control
Author: Bruce R. Archambeault with contributions by James L. Drewniak
Publisher: Springer
ISBN: 978-1-4020-7130-0

When I first read the table of contents for this book – I saw a number of chapters that seemed interesting – and then when I saw the title of Chapter 4, “The Ground Myth”, knew I had to have a copy! I wondered, what kind of book is this that the author would make this type of statement? After I received my copy, I then realized that this was not “just another” EMC book on printed circuit boards (PCB); this was a PCB book about EMC.
This book is intended for the engineer or designer that has had a background in the fundamentals of EMC, component and system design, and it discusses the impact of the “real world”, where time and schedule pressures are sometimes allocated a higher priority over EMC. Interestingly, the title itself, with its use of the phrase “Real-World” seems also to generate interest from people who do not have a background in EMC, all they know is that it’s important (for some reason).
The book is comprised of 13 chapters, and one appendix, with each addressing a different aspect of how to meet EMI requirements. The content of each chapter and appendix are as follows:

Chapter 1, “Introduction to EMI/EMC Design for Printed Circuit Boards” gives the “50,000 foot” overview of the major items that are important when products are identified to have applicable EMC requirements. This chapter also effectively “sets the stage” for the detailed discussions in the remaining chapters.

Chapter 2, “EMC Fundamentals” addresses specific themes in EMC fundamentals, and relates those themes directly to printed circuit board design. The key concepts are introduced: signal spectra, electric and magnetic fields, and why knowledge of PCBs is important. There is also an overview of what some of the potential emission sources are and what their causes are.

Chapter 3, “What is Inductance?” seems to be a question that many people assume they know; for example, they have been taught to believe a straight piece of wire has some property of “inductance” – without an understanding of what this statement really means. This chapter covers the topic in a manner that working engineers will find valuable and the equations included illustrate the correct physical principles very well. This chapter is useful for determination of inductance of long wires and/or conductors that are not typically thought of to have inductance – since they don’t “look” like inductors.

Chapter 4, “The Ground Myth”, in my opinion, even if the rest of the chapters were blank – this chapter alone would be worth having the book. If you want to get puzzled looks from people – show them the title of this chapter! The reader will find themselves reading this chapter again and again to fully understand the implications of this MAJOR PARADIGM SHIFT IN THINKING!

Chapter 5, “Return Current Design” is another area that causes much confusion with the design of PCBs. This chapter, when coupled with the points from chapter 4, provides insight into how critical it is to understand that the return current on a PCB can be unknowingly affected by some the existing “best practices” that are used for layouts of reference planes and interconnection of PCBs.

Chapter 6, “Controlling EMI Sources – Intentional Signals” is an easy to read chapter on the fundamentals of how the intended signals on a PCB can result in EMI issues. The items in this chapter give the engineer/designer insight into the major issues that should be of primary importance when a PCB is being designed, and can provide guidance on initial design practices.

Chapter 7, “Controlling EMI Sources – Unintentional Signals” introduces the concept that the “unintended signals” on a PCB can have a major effect on the ability to meet EMI requirements. These unintended signals can be due to deficiencies in understanding the “grounding” concepts that apply AND DO NOT APPLY, as well as the phenomenon of crosstalk on an actual board, and how that condition may cause EMI compliance issues.

Chapter 8, “Decoupling Power/Ground Planes” addresses the common practice of the rule-of-thumb for decoupling – “just use a bunch of 0.1 mF capacitors and everything will be fine.” This chapter demonstrates how, as a minimum, that rule of thumb may be misleading, and at a worst case, can actually result in a degraded performance than if the decoupling capacitors were not used at all! This chapter clearly shows the author’s experience in real-world decoupling issues.

Chapter 9 addresses “EMC Filter Design”. With the advances in digital signal processing, it seems like much of the fundamentals of filtering techniques have been “put on the back shelf.” This chapter describes how to design filters for effective EMI control and also includes the important aspects of how filter performance is affected by “non-ideal” component characteristics.

Chapter 10, “Using Signal Integrity Tools for EMC Analysis” is a useful topic since the operating speeds of today’s digital devices are ever-increasing, the signal rise/fall times are decreasing, and it means that the fundamentals of EMI analysis become applicable for the study of signal integrity. The chapter contains a number of figures that illustrate how important it is to understand the actual impedance of high speed circuitry and how EMI analysis techniques can help to identify how the system is actually functioning – which may be different from what the engineer believes!

Chapter 11, “Printed Circuit Board Layout” is a continuation of some of the topics that were introduced in chapter 8. This chapter is a “must read” for all who have been taught to focus on the circuit design (such as component selection only) and typically are never made aware of the ability of the PCB to “make or break” the EMI compliance of the design. There is a good discussion of how to allocate PCB board layers, from simple one and two layer boards to the more common six layer designs.

Chapter 12, “Shielding in Enclosures with Apertures” addresses the fact that, sometimes, despite the best intentions of designers and engineers, the only method to achieve EMI compliance may be through the use of shielding. Unfortunately, there seems to be much confusion with regard to what shielding is and is not (for example, what is a “good shield”?). This chapter explains how knowledge of current flow can be used to understand and determine the correct shielding solution to use, and provides basic equations to determine the effectiveness of those solutions.

Chapter 13, “What To Do if a Product Fails in the EMC Lab” should catch the eye of those immersed in the “real world” of EMC. Key to developing any EMI solution is understanding the performance of a design. This chapter contains a number of tips as to what steps to take in identifying the source of the problems – which at that point will then allow the engineer to re-visit the other chapters in the book to determine effective solutions.

Appendix A, “Introduction to EMI/EMC Computational Modeling”. Given Dr. Archambeault’s work in EMC/EMI modeling, it is not surprising to see an introduction to modeling in this book. This appendix does an effective job of “de-mystifying” this complex topic and should serve to help engineers in understanding what basic approaches are used in modeling and the value of those techniques.

The positive aspects of this book are:
- Numerous examples in real PCB design to emphasize the points.
- The chapters can be read on an “as needed” basis; as the engineer/designer is working on a project, they can quickly go to a specific chapter and topic as a resource.
- Easy to read figures and illustrations.
Items that don’t work as well include:
- Significant variation in the number of chapter references – some chapters have many references, others very few, and the reader is left wondering if chapters with few references are based on other material, or is the author’s opinion.
- Additional background with regard to many of the equations would provide the reader with a better understanding and insight at times.
- There are a number of editorial issues (such as typographical and/or formatting) that seem like they should have been caught in the proofreading process.

Overall – I have found this book to be a useful addition to my personal library and have used it both in my EMC product engineering work and identified some of its key points to my past students. I would definitely recommend this book!Mark Steffka, B.S.E., M.S., is with the Electromagnetic Compatibility (EMC) Engineering Group of General Motors (GM) Powertrain and is a faculty member of two universities in the Detroit area. He has over 25 years of experience in the design, development, and testing of military, aerospace and automotive electronics, including power, control, and radio frequency (RF) systems. As an adjunct lecturer at the University of Michigan – Dearborn, and an adjunct professor at the University of Detroit – Mercy, he teaches both undergraduate and graduate level courses on EMC, communications, and antennas. He is a member of the Institute of Electrical and Electronics Engineers (IEEE), has served as an invited session chair for the IEEE EMC Symposium and is the Technical Program Co-Chair for the 2008 IEEE International Symposium on EMC. He has also been a technical session organizer for the Society of Automotive Engineers (SAE) World Congress and has been an invited speaker at IEEE and SAE conferences held in the United States and international locations. His technical publications and presentations have covered topics on EMC, RFI, and he is a co-author of the book Automotive Electromagnetic Compatibility. The paper he presented at the 2007 SAE World Congress titled “Engine Component Effects on Spark-Ignition Caused Radio Frequency Interference (RFI)” was “Judged to be among the most outstanding SAE technical papers of 2007.” He has held an amateur radio license since 1975, with the call sign WW8MS, is a Life Member of ARRL, the National Association for Amateur Radio, and serves on the ARRL EMC Committee. EMC

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