When it comes to PCB design and the topic of electromagnetic compatibility (EMC), the industry insider who is always at the top of the list is Dr. Todd Hubing. He has spent a number of his years in both academia and industry. He is a professor emeritus at Clemson University and has his own consulting firm, LearnEMC through which he provides training and engineering consulting services.
Today, Todd focuses on the automotive industry and the various electronic products that will be incorporated into the future as well as current automobiles.
At Speeding Edge, we continue to use the results of Todd’s research in our consulting efforts as well as the courses that we conduct at industry technical conferences and individual corporations. We have also cited Todd’s research work, and data learned in our two books, “Right The First Time, A Practical Handbook on High Speed PCB and System Design, Volumes 1 and 2.” The real beauty of Todd’s EMC experience is that he has focused on publishing information on EMC issues and backing up that information with test results and hard data that reflects what happens in real hardware.
This article describes Todd’s background in both academia and the wider PCB industry. Specifically, it includes the type of EMC issues that he is encountering in today’s automotive end-application areas, the knowledge gaps he sees in the industry and the types of training he provides.
Todd Hubing Background
As noted above, Dr. Hubing is a Professor Emeritus of Electrical and Computer Engineering at Clemson University and President of LearnEMC. He holds a BSEE degree from MIT, an MSEE degree from PurdueUniversity and a Ph.D. from North Carolina State University. He was an engineer at IBM for seven years and a faculty member at the University of Missouri-Rolla for 17 years before joining Clemson University in 2006. As the Michelin Professor of Vehicle Electronics at Clemson, he established the Clemson Vehicular Electronics Laboratory where he supervised research projects and taught classes in vehicle electronics, electromagnetic compatibility and digital signal integrity. At LearnEMC, he provides EMC instruction, consulting and design assistance to engineers working in the automotive, aerospace and consumer electronics industries. He is a Fellow of the Institute of Electrical and Electronics Engineers (IEEE), a Fellow of the Applied Computational Electromagnetics Society, and a Past-President of the IEEE Electromagnetic Compatibility Society.
About Clemson University
Clemson University is a Carnegie R1 public research institution located in the town of Clemson in upstate South Carolina. It offers 80 undergraduate majors and 130 graduate degree programs across a broad spectrum of the arts, science and engineering to name a few. There are 131 institutions that are classified as “R1: Doctoral Universities – Very high research activity” in the Carnegie Classification of Institutions of Higher Education. These universities have a very high level of both research activity and per capita in such research activity, using aggregate data to determine both measurements.
About LearnEMC
As previously mentioned, upon his retirement from Clemson, Todd founded his own company, LearnEMC. LearnEMC helps companies build the in-house expertise they need to ensure their products will meet electromagnetic compatibility requirements. This is accomplished through EMC short courses and/or working directly with a company’s engineers to design a product guaranteed to meet all EMC requirements.
Short courses cover EMC topics ranging from fundamentals to advanced design and modeling techniques. More information about the consulting resources and courses available through LearnEMC can be found on the company’s website, LearnEMC.com.
EMC Issues Today
In terms of the kinds of PCB designs that Speeding Edge is involved in, the EMC problem is less of a concern than it was in previous designs. But, with his unique vision into the automotive product sector, Todd notes, “EMC is as much of a problem today as it ever has been. We know a lot more than we did 24 years ago, but the challenges have gotten bigger. The sheer number of electronic devices, many of them with intentional transmitters and receivers, is growing exponentially. It has affected every market sector, but automotive and consumer electronics have been particularly impacted.”
EMC and The Automotive Industry
It’s an accepted dynamic that today’s modern cars can often be classified as more computer than car. This can be seen in figure one. There are banks of computers in an automobile that comprise their own networks that have to interface with other networks and computers within the automobile as well as other technologies external to it. The evolution of this technology is happening at almost a blinding rate of speed to encompass such features and capabilities as enhanced safety functionality, autonomous driving and access for the vehicle driver across a variety of technologies and applications. This technology operates at a variety of voltage levels, has a wide range of connectivity requirements, and has to perform in harsh operating environments.
Figure 1. Dr. Hubing and Ph.D. Student, Dexin Zhang, Making Measurements in an Automotive Interior
with Exposed Wiring.
In terms of meeting the EMC requirements that span the spectrum of vehicle operation, Todd notes, “The requirements are evolving to meet the new technologies being offered. In some ways, the requirements are becoming more difficult to meet. We have more things that might interfere. When automotive EMC immunity requirements were developed back in the 80s and 90s, they didn’t give much thought to interference from sources such as cell phones, and bluetooth transmitters because they didn’t exist. The original immunity requirements were focused on AM/FM radio, radar, and similar old fashion kinds of technologies. Now, if you are designing automotive electronics, you have got to ensure that you are not going to have an interference problem with any of the transmitters that people are installing or bringing into cars today.” Figure 2 shows Todd and an undergraduate student inspecting a circuit developed to control an automotive actuator during an EM immunity test.
Figure 2. Dr. Hubing and an Undergraduate Student Inspect a Circuit Developed to Control an
Automotive Actuator During an EM Immunity Test.
In terms of the different automotive PCB products being developed, they range from 12-14 high-speed multilayer boards down to 2-layer sensor boards. Todd explains, “We have a whole range of stuff all packed together in a small volume, and it’s mobile so it’s conceivable that it can go into every kind of electromagnetic environment. And then there is the safety issue which makes everything that much more important.”
“Automotive boards doing high-speed communications are up to 12-14 layers, and they have to be immune to 100 to 200 volts per meter,” he adds. “Generally, these boards are not shielded because they have manufacturing volumes in the millions and the designs are cost-driven.”
I asked Todd if he thought that the broad range of products being designed today and the experience of the engineers doing these designs means that the EMC issues associated with automotive products are beginning to dwindle. He explained, “Significant challenges include the move to autonomous and semi-autonomous vehicles. This is placing a lot more emphasis on the reliability and electromagnetic compatibility of the electronics. We’re also seeing a tremendous increase in the percentage of automotive electronics that rely on wireless communication and automotive Ethernet.”
In terms of the knowledge database, he feels that the information and techniques to develop EMC-compliant systems are well-established. He points out, “Some of the companies I work with have a pretty good handle on it. Their products routinely meet EMC requirements without patches or redesigns. However, technology is advancing. Just when you figure something out, something new comes along presenting a new challenge. I am not sure that we will get to the point that it all becomes automatic, but we will definitely get to a point where failing to meet an EMC requirement is no longer an acceptable part of the design process.”
In terms of how he views automotive technology evolving over the next five years, he predicts, “I believe that we will see considerably more autonomous vehicles being used for defined-route applications such as delivery trucks and taxis. However, this is not coming as fast as many people think.”
“From the EMC perspective, we’re already seeing more pressure for electronics components to comply with EMC requirements on the first pass. Products that fail EMC tests and are then redesigned to comply tend to be less reliable and cost too much. Those automotive suppliers that routinely meet EMC requirements on the first design pass have a significant advantage over those that don’t.”
He continues, “In addition, in the next three to five years, I think we’re going to see more of an emphasis on design and less on troubleshooting. When I interviewed for my first job in EMC in 1982, the department manager told me their objective was to address EMC during the design stage so that it wasn’t an issue in production test. 38 years later, I’m hearing the same thing.”
Knowledge Challenges
Todd notes that the bulk of the EMC issues that pop up are at the board level. He explains, “People get system-level grounding wrong in automobiles all the time, and that makes it that much more difficult to meet requirements by doing things differently on the board. For the most part, most of the people I work with are designing the electronics; they are tier-one suppliers to the OEMs–the automotive manufacturers. The OEMs make grounding and system-level decisions that the people I work with have to deal with at the board level.”
He adds, “In my view, I think the main problem is that people confuse ground with current return. They try to apply the rules of their current return to ground and the rules of grounding to current returns. As a result, they end up doing crazy things in their board layouts. In my experience, people who know absolutely nothing about EMC tend to design better circuit boards than people who are working from a set of EMC design rules.”
As noted in previous articles, at Speeding Edge, we emphasize that the benefits gained from using various design tool sets are dependent on the level of understanding that people have when they use those toolsets.
Todd explains, “One of the courses I teach discusses the kinds of modeling you can do and the questions you can answer. There is a need to put numbers on things to know that the design is going to be compliant, and that’s where tools can be used.”
He continues, “You can use numerical modeling tools to model a very specific structure with exact boundary conditions, and they will give you the exact solution for that particular thing. For signal integrity (SI), numerical modeling tools work really great because we know the source, we know the termination; we control the transmission line. We know everything that is important, and we control everything that is important. So, we can model, for SI, very accurately and in fact, you pretty much have to use modeling tools to do SI properly.”
But that is not the case when it comes to EMC and radiated fields. Todd notes, “It’s true that numerical modeling tools can be very helpful for getting an understanding of the way EMC works, what constitutes a good radiating structure and, in a general sense, what’s not a good radiating structure. But, full-wave, numerical tools are not helpful when it comes to actually designing and laying out the product. At the design stage, we need to do worst-case calculations.”
He adds, “For EMC, you can’t learn what the important things are from your numerical modeling tool. Little details end up being critically important and if you didn’t model everything exactly right (or even if you did model everything exactly right), your cable, which you don’t control, won’t be in the same position during the test, and you will get a very different result. For EMC, we don’t want the exact solution. We want to know the worst-case solutions. We want to know that our product attached to any cable harness, in any of its intended vehicles, tested in any test lab won’t cause an emissions or immunity failure.”
Bridging The Gap Between Education and Building Working Hardware
As noted in previous articles, at Speeding Edge we find that there is often a knowledge gap between what graduating engineers learn in university courses and what they need to know when they transition to designing real hardware. Todd agrees with this assessment.
He states, “There’s a definite knowledge gap in the case of EMC. Very few universities offer even a single course in EMC. Most engineering students have no idea what EMC is much less how to design products to meet EMC requirements.”
He continues, “I was a faculty member for almost 40 years. I was at universities that taught EMC, but there are very few universities that offer an EMC course. In Rolla and Clemson, we had EMC labs, and we had graduate students doing EMC research. But even at those universities, most students getting an EE degree never take an EMC course. As a result, they are not getting the training they need to design EMC-compliant products.”
Todd puts a caveat on the foregoing. He states, “There’s an awful lot of really important stuff that engineering students have to learn in four years. Undergraduate electrical engineering is necessarily pretty general with few opportunities to specialize. Most graduates will never design and layout circuit boards, so EMC is not a priority. In fact, some electrical engineering programs no longer require an electromagnetics course. When I started teaching at the University of Missouri-Rolla (now Missouri S&T), electromagnetics was two semesters. First, you studied statics and then dynamics, so you had two required electromagnetics courses. But by the time I left, only one course was required, and if you focused on computer engineering, you didn’t even have to take that one.”
He adds, “If you have never even heard of a transmission line or Maxwell’s equations, you are not going to be very effective as an SI or EMC engineer. These topics are difficult to pick up on your own or in short courses. On the other hand, if you take a university course and you work the homework assignments and take the exams, eventually it all sinks in.”
As a consultant, Todd sees that more of his time right now is devoted to training as opposed to engineering consulting. He explains, “Prior to the pandemic, the split between training and consulting was about 50/50. We were doing some of our courses for companies online. But with the pandemic, the demand for online went through the roof. Most of my time has been devoted to teaching open enrollment online courses and private online courses for companies.”
“We generally limit our class sizes online, so it’s very interactive. I can see everybody’s face, and they can see me. I can usually see that someone has a question even before they ask it. I have students all over the world, and even if a student is on the other side of the globe, we can generally interact as though we were in the same room.”
He states, “Fortunately, prior to the pandemic, we were already teaching courses online, so it wasn’t a major step for us to move 100% of our training online. When we emerge from the pandemic, I don’t anticipate much of a change in our business plan. People are learning that online education can be just as effective and much more affordable than on-site education. “
“I also believe universities and university faculty are starting to realize that some percentage of their courses can be taught online. There is also a growing acceptance of online teaching. I believe this will encourage more people to pursue graduate degrees as well as other types of continuing education.”
Summary
The widespread deployment and diversity of electronics being used in automotive technologies have once again made EMC a topic of concern at the board level. Understanding the dynamics of the various automotive environments; what EMC is, how it functions in these environments and what is needed to build real-world working hardware will prepare the industry for what lies ahead in the product generations yet to come.
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