[Editor's Note] Electromagnetic noise generated during IT product design can cause fatal defects, including reduced product performance and malfunctions. Recent trends such as the electrification of automobiles, the miniaturization of various IT devices, and the paradigm shift toward 5G and 6G communications have led to an increase in noise in the electromagnetic environment, leading to malfunctions in various devices and systems. Accordingly, through the planned serial series 'EMI/EMC Expert Talks', we have highlighted the importance of EMI/EMC countermeasures for the development of safe and reliable cutting-edge IT products, and have created an opportunity to meet EMI/EMC experts from various fields and hear their latest stories.

We met with Professor Ji-Sung Kim, a visiting professor at the KAIST Green Transportation System Research Center, the first interviewee for the EMI/EMC expert dialogue.

[Reporter] Please introduce yourself briefly.

Professor Kim Ji-seong received his doctorate from the University of Texas and worked in high-speed digital system design at Samsung Electronics. He later served as a professor at Suwon Science College and is currently a visiting professor at the KAIST Green Transportation System Research Center.

My research focuses on electromagnetic interference (EMI/EMC) in high-speed digital systems and power systems. These technologies are crucial for reducing noise generated during electronic product design and minimizing harmful electromagnetic waves, ensuring high-reliability designs.

We are also researching interconnect design for high-speed signal transmission, and this technology is required in all fields that involve electronic circuits, including semiconductors, IT, home appliances, automobiles, military, and aviation.

[Reporter] I'm curious about your recent activities. What activities are you doing?

[Professor Kim Ji-seong] Recently, I have been focusing on academic and industry-academia activities.

As a specialist in my field of research, I serve as a research fellow for the EMC Research Group of the Korean Institute of Electromagnetic Engineering and Science, as well as the High-Speed Interconnect and Packaging Research Group. I frequently lecture and provide advice on related technologies to employees at large domestic companies and small and medium-sized enterprises.

The EMI/EMC field is an essential technology for product development for companies ranging from small and medium-sized enterprises to large corporations. However, small and medium-sized enterprises in particular face difficulties in internalizing the technology and require significant assistance from external experts. Therefore, while I am constantly learning and researching new technologies, I am also striving to contribute more to the industrial field based on my experience and knowledge to date.

[Reporter] What are some of the hottest EMI/EMC issues these days? If you're interested in any of the latest countermeasure technologies, please share them with us.

[Professor Kim Ji-seong] A recent hot topic is the electrification of automobiles, which is resulting in an increase in electromagnetic waves, especially in areas such as power circuits, and increasing issues in high-reliability design.

In particular, noise generated from motors/inverters is relatively more frequent, and most of the components are electronic, making signal integrity (SI), power integrity (PI), and EMI/EMC design increasingly important.

Another hot topic is the semiconductor industry. While semiconductor IC design is important, both academia and industry are actively researching and developing chiplet technology, which connects individual chips with different functions—CPU, GPU, power, I/O, and memory—into a single package.

These 2.5D/3D advanced packaging technologies are important not only for their fine processes and materials, but also for their connection structures and interconnect design. The convergence of diverse research fields, including materials, machinery, and semiconductor engineering, is essential technology, and SI, PI, and EMI/EMC technologies are also crucial. Optimal interconnect design is crucial for connecting individual chips with various functions and transmitting high-speed signals.

[Reporter] Recently, there seems to be a noticeable trend toward higher switching frequencies while reducing system size to achieve greater efficiency. What are the EMC considerations in this context?

[Professor Kim Ji-seong] When developing a switching power system (SMPS), it is difficult to consider efficiency, performance, and electromagnetic waves.

To increase efficiency, the most important performance indicator, switching speeds can increase electromagnetic noise. Furthermore, reducing noise requires additional components, driving up the price. However, electromagnetic compatibility design is essential for product launch and must be considered alongside various performance indicators from the design stage.

Looking at technology trends, switching frequencies are increasing in the mobile sector to miniaturize power circuits, and on-chip DC-DC converters are being developed. While higher frequencies allow for smaller components, they also increase electromagnetic interference (EMI) issues, such as interference with communication frequencies. Therefore, EMI must be considered during the design phase.

The main noise in power circuits comes from switching devices such as MOSFETs, but recently, wide-bandgap devices such as SiC and GaN devices are being widely used. Since changes in the characteristics of these devices along with changes in frequency also affect the generated noise, much research is being conducted in the field of EMC.

[Reporter] I heard that electric vehicles are showing a trend toward integrating systems for efficiency, such as integrating the OBC and converter, but noise is also a significant problem.

[Professor Kim Ji-seong] In the case of high-voltage, high-power systems like automobiles, the generated noise is relatively large, making countermeasures challenging. Especially when switching circuits at multiple frequencies are integrated and designed, or when low-voltage, high-voltage, sensor, and communication circuits are packaged together in a single housing, electromagnetic noise can easily couple between circuits within the housing, making it difficult to address conducted and radiated noise, as well as designing for high reliability.

Because these issues are difficult to address after development, it is important to consider them from the early stages of design.

[Reporter] Professor, your most recent academic research publication is "Digital Communication Using Contactless Interconnects." What is it about?

[Professor Kim Ji-seong] We have been promoting the 'Development of Advanced Power and Signal EMC Technology for Hyper-Connected E-Vehicles' project, supported by the Ministry of Science and ICT, for the past four years. Through this project, I am conducting research on electromagnetic technology required for future electric vehicles, and one of the research projects I am conducting is on contactless high-speed interconnect.

It is a technology that transmits signals through a short-range non-contact interconnect without transmitting signals through a connector, and is different from wireless communication that uses antennas in that it transmits signals using near-field capacitive coupling.

Recently, commercial ICs that transmit high-speed digital signals at 10 Gbps using 60 GHz millimeter waves and antennas have been released, and a related market is forming. This technology transmits high-speed digital signals without direct connection through connectors, requiring RF components and antennas. My research utilizes capacitive coupling between adjacent conductors, making it possible to implement it inexpensively and potentially useful in areas like automotive applications.

[Reporter] What progress has been made with additional research and development since the announcement?

[Professor Kim Ji-seong] We've already implemented CAN/LIN communication for automotive use, and recently, we've developed LVDS communication, which is used as an interface for camera modules. Going forward, we plan to research technology that can transmit data at speeds up to several Gbps using the vehicle's body.

[Reporter] With the development and application of advanced non-contact interconnect technologies, as well as wireless power transmission, short-range wireless communication technologies, and IoT, across society, it seems that the era of massive wireless and hyper-connected society is deepening. In this deluge of radio technology, what do you think are the EMI/EMC issues that need to be addressed and prepared for?

[Professor Kim Ji-seong] As briefly mentioned earlier, many wireless communication technologies are emerging, and frequencies are constantly increasing. Consequently, regulations are constantly being added and revised to prevent electromagnetic noise from interfering with these frequencies.

For example, digital communication transmission speeds are increasing. USB, for example, currently operates at 10 Gbps, but even faster speeds are expected. The frequencies generated by these digital signals easily interfere with Wi-Fi, GPS, and other technologies.

The switching noise of the power circuit mentioned above can easily affect communication frequencies in the AM/FM band. Therefore, the EMI/EMC field is continuously researching countermeasures to address emerging technologies, including changes in wireless communication technology.

[Reporter] What are your plans and goals for the future?

[Professor Kim Ji-seong] I'm personally continuing my research in related fields, but going forward, I'd like to focus on fostering experts in the EMI/EMC field. This field requires field-oriented skills essential to industrial settings, but related training programs are lacking, and because it requires extensive experience alongside theoretical knowledge, fostering experts is challenging.

In this field, our country has already secured technology that is not behind that of advanced countries. To secure national technological competitiveness, we need many experts in this field. Based on our knowledge and experience to date, we aim to contribute to the development of experts in this field through education and technical consulting.

[Reporter] This is already our last question. What is your outlook for the future of the EMI/EMC field?

[Professor Kim Ji-seong] Technological change is accelerating, and recently, new technologies like AI are having a significant impact on society. While EMI/EMC technology hasn't received much attention amidst this shift, it is essential for any technology or product. Therefore, I believe the demand for EMI/EMC technology will remain constant, from the past to the present, and into the future.

thank you