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Engineer Column

Harmonizing Circuit Design and EMC Design


Launching a New Column: "Harmonizing Circuit Design and EMC Design"

How do you do! My name is Inagaki, and I'm with ROHM.
I've been fortunate enough to have the opportunity to meet with you all on this page each month.
When designing LSIs and equipment, there is generally some conflict between circuit design, in which electrical characteristics are brought into conformance with the product specifications, and EMC design, which must conform to international EMC standards. Hence an aptitude for balance is required.
In this column on EMC, I would like to convey, at least to some extent, this sense of balance, a kind of "harmony" between these design demands.
I hope you will find this column useful.

I'll begin by introducing myself.

I joined ROHM over 30 years ago. I was assigned to a design department for semiconductor integrated circuits (ICs). At that time bipolar ICs were the mainstream, and the process rule (the width of the metal layer wiring) was 10 μm (microns). The number of elements was also only about 100 or so, and semiconductor integrated circuits (ICs) were more or less being made by hand, as it were. Circuit diagrams were drawn by hand on graph paper, and electronic components were soldered onto a temporary board, called a breadboard, to check operation. There were no circuit simulators; it was an era in which the results of calculations using pocket calculators were compared with measurements using breadboards to design circuits. The CAD data to create glass masks for mass production were also drawn manually, and the primitive circumstances of the day were such that digitizers were used to read in data. Time flowed rather slowly back then.

But our superiors and supervisors were quite strict. I recall that they were rather merciless, or so it seemed, when addressing errors in theoretical equations and manual calculations. Likewise with measurements, I was cautioned in detail about the positioning of probes. This was an era without microcomputers or the internet, so information relating to design had to be culled from commercially available books or acquired by asking our bosses and superiors.

These circumstances were also resolved with time. Circuit simulators were introduced, microcomputers were installed, and an ideal design environment gradually took shape. I created simulation models by myself, extracted parameters, and determined model parameters to run circuit simulations. Through comparisons with measured values for "mono kits" (packages containing only a single transistor), it was possible to check the effects of different parameters in a simple manner.

One strength of ROHM's had been custom ICs which met all the needs of our customers, and I myself was involved in the development and mass production of perhaps 20 types of custom ICs. This was a very good experience. A first prototype was used to check basic operation, and a second prototype was used to obtain characteristics. A third prototype was preparation for volume production, and in this manner, we developed analog ICs for audio and video, and analog/digital ICs. Some of the semiconductor ICs we developed in that period are even today being mass produced.

After awhile I was transferred to Tokyo and was loaned out to research labs, and also had the opportunity to participate in joint research with universities. From around this time, it was one culture shock (how archaic!) after another. I also attended overseas conferences: major foreign competitors discussing competing technologies with each other! I could hardly believe I myself was in the same room with them. In this joint research, simulation models were hammered out in extensive detail. It was in this period that I acquired all the fundamentals--how to write research papers, tips for giving presentations, how to conduct meetings, and so on.

When I was no longer dispatched to research labs, I undertook work relating to electromagnetic compatibility (EMC). My first impression was that this was a field I felt I couldn't really understand very well. This is my twelfth year working in this field. Having handled various kinds of tasks, I have come to understand that electromagnetic compatibility (EMC) is not a deep mystery or anything, but is rather involves problems that can be solved fairly logically. I also discovered that an understanding of circuit operation can be applied to quite a lot in this field.

On the basis of these experiences and knowledge accumulated over thirty-odd years, I would like to present a wide-ranging view of semiconductor integrated circuits (ICs) and electromagnetic compatibility (EMC) without becoming too caught up in details, in order to convey the essentials in an easy-to-understand manner. I am planning a two-part series that will include introductory articles explaining ICs and EMC in simple terms, and intermediate articles that explain electromagnetic compatibility or EMC in some depth. I hope to present things in a manner that can be grasped intuitively, so please be sure to stop by!

Thank you for your interest, and see you next time.

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