The Bridge - Issue 2, 2022 - 28

Feature
Mitigating Self-generated EMI for Wireless Devices
(a)
(b)
Fig. 6. Measured RFI reduction for the right-side antenna between the modified design and the original design [7].
IV. Conclusion
The antenna susceptibility at the noise source
location must be determined, but in this case, our
concern is the angle rather than the magnitude
of the antenna susceptibility vector, namely Hy in
this example. According to measurements, the Hy
vector has an angle of approximately 63°, and the
rotation angle is determined to be 27°. The device
with the new placement was fabricated as shown
in Fig. 6(a) in collaboration with Amazon Lab126
Wireless Technology Group. The coupled voltages in
the Wi-Fi frequency band for the original design and
the rotated design are shown in Fig. 6(b) [7]. The
measured data successfully validates the proposed
mitigation methods.
REFERENCES
1. " Electromagnetic fields and public health: mobile phones " ,
World Health Organization, Fact sheet N°193, May 2010
2. A. Scogna, H. Shim, J. Yu, C.-Y. Oh, S. Cheon, N. Oh, and D.
S. Kim, " RFI and receiver Sensitivity analysis in mobile electronic
devices, " DesignCon 2017, Santa Clara, CA, Jan 21-Feb 2, 2017.
3. http://www.amberpi.com/
4. Q. Huang, L. Zhang, Y. Zhong, J. Rajagopalan, D. Pai, C. Chen, A.
Gaikwad, C. Hwang, and J. Fan, " A Fast and Simple RFI Mitigation
Method without Compromising Signal Integrity " DesignCon 2019,
Santa Clara, CA, Jan. 28-30, 2019.
5. Q. Huang, T. Enomoto, S. Seto, K. Araki, J. Fan, and C.
Hwang, " A Transfer Function Based Calculation Method for
Radio Frequency Interference " IEEE Trans. on Electromagnetic
Compatibility, vol. 61, no. 4, pp. 1280-1288, Aug. 2019.
6. https://www.allaboutcircuits.com/news/teardown-tuesdayamazon-echo-dot-v2/
7.
Q. Huang, L. Zhang, J. Rajagopalan, D. Pai, C. Chen, A. Gaikwad,
C. Hwang, and J. Fan, " A Novel RFI Mitigation Method Using
Source Rotation " IEEE Trans. on Electromagnetic Compatibility,
vol. 63, no.1, pp.11-18, Feb. 2021
THE BRIDGE
Self-generated EMI problems are becoming
common and critical in wireless device design.
The RF range can substantially change, depending
on EMI performance. A theorical background for
the electromagnetic framework, incorporating the
radiation source and intra-system coupling models,
was introduced here. Based on this framework, new
approaches to mitigate the self-generated EMI were
explained and demonstrated by using a real device.
Chulsoon Hwang (S'08-M'13-SM'18)
received the B.S., M.S., and Ph.D.
degrees in electrical engineering from
the Korea Advanced Institute of Science
and Technology (KAIST), Daejeon,
South Korea, in 2007, 2009, and
2012, respectively.
He was with Samsung Electronics,
Suwon, South Korea, as a Senior
Engineer from 2012 to 2015. In July 2015, he joined the
Missouri University of Science and Technology (formerly
University of Missouri-Rolla), Rolla, MO, USA, where he is
currently an Assistant Professor. His research interests include
RF desensitization, signal/power integrity in high-speed digital
systems, EMI/EMC, hardware security and machine learning.
Dr. Hwang serves as the Vice Chair of the SC-5 Power Electronics
EMI of the IEEE EMC Society and an associated editor for the
IEEE Transactions on Signal and Power Integrity. Dr. Hwang was
a recipient of the AP-EMC Young Scientist Award, the Google
Faculty Research Award, and Missouri S&T's Faculty Research
Award. He was a co-recipient of the IEEE EMC Best Paper Award,
the AP-EMC Best Paper Award, and a two-time co-recipient of the
DesignCon Best Paper Award.

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The Bridge - Issue 2, 2022

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