| Project/Area Number |
11834008
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Institution | Okayama University |
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Principal Investigator |
WADA Osami Okayama University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (10210973)
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| Co-Investigator(Kenkyū-buntansha) |
MIYASHITA Takuya Okayama University, Computer Center, Research Associate, 総合情報処理センター, 助手 (70304300)
TOYOTA Yoshitaka Okayama University, Graduate School of Natural Science and Technology, Research Associate, 大学院・自然科学研究科, 助手 (20311798)
KOGA Ruji Okayama University, Faculty of Engineering, Professor, 工学部, 教授 (20027147)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | printed circuit board / near-field measurement / EMI / EMC / far-field / bus line / clock line / simulation |
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| Research Abstract |
This research is to investigate prediction of far-field EMI (Electro-Magnetic Interference) from printed circuit board (PCB) by means of near-field measurement. Particularly, radiated emission from "bus lines" and "clock lines" on a high-speed digital PCB has been investigated.
First, radiated emission from a single clock line with a finite ground plane is measures in far field. Each of the test boards has rectangular cuts on a ground plane, and ground width of a return path just under the clock line is altered. Radiated emission from the test boards is evaluated at a 3m distance from the board in a semi-anechoic room, and the corresponding common-mode current for each test line is also measured. As a result, common mode current and corresponding emission are theoretically predicted that are caused by the difference of unbalance factors of transmission lines. Reduction of common-mode current and emission due to the decrease of ground inductance agrees well with the theory. The results explains required width of the return path on a PCB ground, which can be used in practical design of digital printed circuits.
Next, periodical and random signals on bus lines are investigated. Timing control of signals is proposed for the reduction of EMI, and it is examined with a pair of signal lines. The EMI reduction effect for both of PCBs with wide and narrow ground planes is explained with theoretical calculation and measurements. The technique is also effective for reduction of the common-mode current, near-field and far-field EMI.
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