High-Frequency Performance Analysis and Verification of Twinax Cable Structures

Authors

  • Wei-Hsiu Tsai Department of Electronic and Computer Engineering National Taiwan University of Science and Technology, Taipei 10607, Taiwan
  • Ding-Bing Lin Department of Electronic and Computer Engineering National Taiwan University of Science and Technology, Taipei 10607, Taiwan https://orcid.org/0000-0003-1980-0609
  • Cheng-Hsun Ho Department of Electronic and Computer Engineering National Taiwan University of Science and Technology, Taipei 10607, Taiwan
  • Tzu-Fang Tseng Department of CTO Office BizLink International Corporation, New Taipei 23533, Taiwan

DOI:

https://doi.org/10.13052/2025.ACES.J.401110

Keywords:

Mixed-mode scattering parameters, RLGC parameters, transmission line analysis, Twinax cable, vector network analyzers

Abstract

The most commonly used cables in device-to-device communication, such as USB, HDMI, DP, or PCI-e cables, as well as the MCIO cables currently used in artificial intelligence (AI) servers, has a differential Twinax configuration. The use of differential transmission aims to mitigate the impact of external interference. The Twinax structure consisted of a twin-core cable with an outer copper foil shielding. Achieving perfect symmetry in the Twinax cable is a challenge. This work investigated whether the asymmetrical structure and material impacted the production yield rate. The focus was on the mixed-mode analysis of the asymmetric Twinax cable. By utilizing mixed-mode S-parameters, we aimed to determine whether the cable designs met industry standards and complied with data rate requirements. Due to intense market competition and short development cycles, 3D full-wave simulations were time-consuming because of the high mesh count. Moreover, modeling was challenging because the center of each segment of an actual cable underwent slight variations. To expedite the design process, a method was developed to extract Twinax cable RLGC (Resistance, Inductance, Conductance, Capacitance) parameters, calculate mixed-mode S-parameters, and perform analysis and evaluations. Our approach not only enables efficient signal quality assessment across cables of varying lengths by simply connecting each small segment to account for continuous manufacturing variations but also significantly reduces product development time to under one hour. Furthermore, this work investigated the impact of common manufacturing imperfections, ensuring robust and reliable designs for real-world applications.

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Author Biographies

Wei-Hsiu Tsai, Department of Electronic and Computer Engineering National Taiwan University of Science and Technology, Taipei 10607, Taiwan

Wei-Hsiu Tsai received a B.S. degree in Mathematics from the Fu Jen Catholic University, New Taipei, Taiwan, in 1999, and an M.B.A. degree in industrial management from the National Taiwan University of Science and Technology (Taiwan Tech), Taipei, in 2019. He is pursuing a Ph.D. degree in the department of electronic and computer engineering from the National Taiwan University of Science and Technology (Taiwan Tech) under the supervision of Prof. Ding-Bing Lin. He is currently an Engineer with BizLink International Corporation, New Taipei. His research interests include high-speed transmission techniques and high-frequency measurement techniques.

Ding-Bing Lin, Department of Electronic and Computer Engineering National Taiwan University of Science and Technology, Taipei 10607, Taiwan

Ding-Bing Lin (S’89-M’93-SM’14) received the M.S. and Ph.D. degrees in electrical engineering from National Taiwan University, Taipei, Taiwan, in 1989 and 1993, respectively. From August 1993 to July 2016, he has been on the faculty of the Electronic Engineering Department, National Taipei University of Technology, Taipei, where he was Associate Professor, Professor and Distinguished Professor in 1993, 2005, and 2014, respectively. Since August 2016, he had been with National Taiwan University of Science and Technology, Taipei, where he is currently Professor in the Electronic and Computer Engineering Department. His research interests include wireless communication, antennas, high-speed digital transmission, and microwave engineering. From 2015 to 2018, he served as the Taipei Chapter Chair, IEEE EMC society. He has served as the Taipei Chapter Chair, IEEE AP society since 2022. He also serves as Associate Editor of IEEE Transactions of Electromagnetic Compatibility since 2019 and serves on the Editorial Board of the International Journal of Antennas and Propagation since 2014. He has published more than 250 papers in international journals and conferences. Lin was the recipient of the Annual Research Outstanding Award of the College of Electrical Engineering and Computer Science in 2004, 2006, and 2008. After he received these three awards, the College of Electrical Engineering and Computer Science awarded him the College Research Outstanding Award to highlight his research achievements. He was also the recipient of the Taipei Tech Annual Outstanding Research Award in 2008. Lin is the recipient of the Annual Research Outstanding Award of the National Taiwan University of Science and Technology in 2024.

Cheng-Hsun Ho, Department of Electronic and Computer Engineering National Taiwan University of Science and Technology, Taipei 10607, Taiwan

Cheng-Hsun Ho received the B.S. degree from Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology (NTUST), Taipei, Taiwan, in 2021, and the M.S. degree in Electronic and Computer Engineering from the National Taiwan University of Science and Technology (Taiwan Tech), Taipei, in 2023. His research includes high-frequency measurement and cable model design.

Tzu-Fang Tseng, Department of CTO Office BizLink International Corporation, New Taipei 23533, Taiwan

Tzu-Fang Tseng received the B.S. degree in electrical engineering from National Taiwan University, Taipei, Taiwan, in 2009, and the Ph.D. degree in photonics and opto-electronics from National Taiwan University, Taipei, in 2015. She started working in industry in 2015. Her research interests include MMW signal transmission, signal integrity in high-speed cables and connectors, and optical planar lightwave circuit design and applications.

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Published

2025-11-30

How to Cite

[1]
W.-H. . Tsai, D.-B. . Lin, C.-H. . Ho, and T.-F. . Tseng, “High-Frequency Performance Analysis and Verification of Twinax Cable Structures”, ACES Journal, vol. 40, no. 11, pp. 1133–1144, Nov. 2025.

Issue

2025: Vol 40 Iss 11

Section

General Submission

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