Article
Computer Science, Information Systems
Van-Son Trinh, Jung-Dong Park
Summary: A compact W-band power amplifier for automotive radar application was proposed in 65-nm CMOS technology, with efficient transformer-based matching networks. Operating at 1.3V, the implemented 77GHz PA achieved good performance, demonstrating high power density.
Article
Automation & Control Systems
Jiawen Yu, Lei Wang, Wei Tian, Kai Zhang, Shuhan Liao, Qianming Xu
Summary: This article proposes a shunt active impedance matching network (SAIMN) to achieve adaptive broadband impedance matching for increasing power utilization from a power amplifier to the transducer. The load impedance characteristic and operation principle of SAIMN are introduced mathematically, and a parameter design method is provided to improve impedance matching performance. A compound control strategy is presented to control the power amplifier and proposed SAIMN. The results show that the proposed SAIMN can adaptively match load impedance for the different loads in a broadband frequency range, significantly improving the power factor of the power amplifier and reducing the current stress of the switching device.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)
Article
Automation & Control Systems
Lei Wang, Ying Pang, Wei Tian, Qianming Xu, Shuhan Liao, Jiangtao Yang
Summary: This article presents an adaptive broadband thyristor-controlled impedance matching network (TCIMN) for increasing power utilization from a power amplifier to the loads. The operation principle of TCIMN is introduced mathematically, and a parameter design method is proposed. The simulation and experimental results demonstrate that the proposed network can adaptively match the load impedance and improve power amplifier power utilization.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
Jaehun Lee, Ji-Seon Paek, Songcheol Hong
Summary: This article introduces two millimeter-wave frequency reconfigurable dual-band CMOS power amplifiers for 5G communications, including a single-stage dual-band PA and a two-stage dual-band PA. They cover multiple 5G communication bands through the use of reconfigurable transmission line transformers, achieving optimal performance within small chip areas.
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
(2022)
Article
Computer Science, Information Systems
Van-Son Trinh, Jung-Dong Park
Summary: A high-performance X-band two-stage power amplifier was developed in 65-nm CMOS process using a transformer-based voltage combining technique. The amplifier achieved high output power and power gain under 1.2V supply voltage with a small chip size.
Article
Engineering, Electrical & Electronic
Jiawen Wang, Wei Zhu, Ruitao Wang, Yan Wang
Summary: This letter presents the design of a Dual-mode W-band eight-way power-combining power amplifier implemented in Taiwan Semiconductor Manufacturing Company (TSMC) 65-nm CMOS technology. The proposed PA achieves high output power with high power efficiency using a configurable parallel-series-based eight-way power combine technique. The PA also demonstrates good performance in both high-power mode and low-power mode, with a peak gain of 30.9 dB and a compact core area of 0.3 mm(2).
IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS
(2022)
Article
Computer Science, Information Systems
Roberto Quaglia
Summary: This paper presents a method to improve the accuracy of linear simulators in high-frequency power-amplifier design, by analytically obtaining equivalent mismatch circles that lay within the power or efficiency contours targeted by the design through geometrical considerations.
Article
Engineering, Electrical & Electronic
Jeng-Han Tsai
Summary: This letter presents a fully integrated CMOS power amplifier (PA) with a high-power built-in linearizer, operating at 5.3 GHz frequency with watt-level output power. By utilizing a transformer-based 2-stage dual-radial power splitting/combining structure, the CMOS PA achieves high output power. Additionally, a cascode cold-FET built-in linearizer with high power capacity is developed to enhance the linearity of the CMOS PA. Experimental results show that the CMOS PA achieves high linearity, with the highest P-linear and OP1dB among reported CMOS PAs around 5 GHz to date.
IEEE MICROWAVE AND WIRELESS TECHNOLOGY LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Zonglin Ma, Zheng Ma, Kaixue Ma, Fanyi Meng, Keping Wang
Summary: This paper presents a 28-GHz high-power four-way differential Doherty power amplifier (PA) in 55-nm bulk CMOS technology. A transformer-based hybrid load-modulated combiner (HLMC) is proposed to achieve high output power, low-loss power combining, and a true-Doherty load modulation. The measured results show good performance in terms of output power, efficiency, and error vector magnitude (EVM) for 64-quadrature amplitude modulation (QAM) signals.
IEEE MICROWAVE AND WIRELESS TECHNOLOGY LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Jiaxiang Li, Yun Yin, Hang Chen, Jie Lin, Yicheng Li, Xianglong Jia, Zhen Hu, Ziyu Liu, Xiuyin Zhang, Hongtao Xu
Summary: This article presents a quadrature digital power amplifier (DPA) with IQ-reuse and Doherty techniques, along with an 8-way serial power combined transformer, for high output power and high efficiency. The DPA achieves peak power-added efficiency (PAE) of over 30% across a wide frequency range. For LTE 20MHz 64QAM signal, it achieves high average output power and average PAE at a low error vector magnitude (EVM) limit.
IEEE JOURNAL OF SOLID-STATE CIRCUITS
(2023)
Article
Chemistry, Multidisciplinary
Egidio Ragonese
Summary: This paper reviews the latest design approaches for low-voltage RF and mm-wave CMOS circuits, including body biasing and integrated reactive components. It also discusses the application of low-voltage design techniques in various key RF and mm-wave circuit blocks.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Aerospace
Austin Egbert, Adam Goad, Charles Baylis, Anthony F. Martone, Benjamin H. Kirk, Robert J. Marks
Summary: This article presents an algorithm that performs impedance tuning with an evanescent-mode cavity tuner based on an average performance gradient computed for multiple transmit pulses, effectively optimizing the transmitter for maximum average output power as the radar system transitions between different center frequencies, bandwidths, and waveforms.
IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS
(2022)
Article
Engineering, Electrical & Electronic
Wei Tian, Shuhan Liao, Lei Wang, Xiaoping Zhou, Qianming Xu
Summary: This article proposes an adaptive broadband full-bridge converter impedance matching network for load impedance matching of power amplifiers. The principles of operation, control method, and parameter design method are introduced. The simulation and experimental results validate the effectiveness of the proposed method and show improved power amplifier power utilization factor.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
Hamed Mosalam, Wenbo Xiao, Xiaoyan Gui, Dan Li, Quan Pan
Summary: This paper presents a 54-68 GHz two-stage power amplifier with linearity and efficiency enhancement in a 40 nm CMOS process. The proposed structure and techniques achieve good experimental results in terms of linearity and efficiency.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2022)
Article
Engineering, Electrical & Electronic
Jincai Wen, Meng Yu
Summary: This paper proposes a reconfigurable low noise amplifier (LNA) for 5G dual-bands in a 65-nm CMOS process. The reconfigurable function is achieved through the design of matching networks composed of transformers and MOS transistor switches. The characteristics of the resonant network and the amplifying device are analyzed, and the specific parameters of the reconfigurable matching network are determined based on the relationship between reconfigurable frequencies and the ratio of transformer coil inductance.
ELECTRONICS LETTERS
(2023)
Article
Computer Science, Interdisciplinary Applications
Hyunjin Lee, Sunyoung Bang, Woontack Woo
Summary: This study investigates the impact of effective placement of AR notifications on users' perception and understanding through two studies. The results indicate that different positions and coordinate systems have different effects on the noticeability and comprehension of icon-type and text-type notifications.
Article
Computer Science, Interdisciplinary Applications
Dooyoung Kim, Seonji Kim, Jae-eun Shin, Boram Yoon, Jinwook Kim, Jeongmi Lee, Woontack Woo
Summary: In this study, we explored how spatial configurations affect the threshold range of Relative Translation Gains (RTGs) for a Redirected Walking technique in Virtual Reality. Through participant responses and gaze distribution data, we found that room size, the presence of objects, and spatial layout all significantly impacted the RTG threshold range. Based on our findings, we proposed guidelines for rescaling virtual space to increase the available movable space for developers.
Article
Computer Science, Interdisciplinary Applications
Cholmin Kang, Inhwa Yeom, Amirsaman Ashtari, Woontack Woo, Junyong Noh
Summary: This study investigated the needs and issues of older wheelchair users in outdoor activities and proposed ARbility, a wearable AR-based shopping system. ARbility supports product recognition and one-stop shopping functionality for wheelchair users, reducing physical loads. User evaluation showed a 33% decrease in arm movement, with participants validating its effectiveness and usability. The study concludes with implications on how a wearable AR-based shopping system supports active aging and inclusion of older wheelchair users.
Article
Computer Science, Software Engineering
Boram Yoon, Jae-eun Shin, Hyung-il Kim, Seo Young Oh, Dooyoung Kim, Woontack Woo
Summary: This study compared the effects of avatars with different transparency levels on the social presence of users in task-centric MR remote collaboration in AR and VR. Results showed that avatars with a strong visual presence are not necessary when task completion is prioritized over social interaction. However, AR users preferred more vivid avatars than VR users.
IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS
(2023)
Article
Computer Science, Software Engineering
Hyung-il Kim, Boram Yoon, Seo Young Oh, Woontack Woo
Summary: In this paper, a prototype system for sharing a user's hand force in MR remote collaboration on physical tasks is presented. The system uses a wearable sEMG sensor to estimate hand force and visualizes it for the expert. A user study demonstrates that sensing and sharing hand force improves the expert's awareness, perception, and social presence in the collaboration.
IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS
(2023)
Article
Computer Science, Interdisciplinary Applications
Maryam Shakeri, Hyerim Park, Ikbeom Jeon, Abolghasem Sadeghi-Niaraki, Woontack Woo
Summary: This paper proposes a personalized recommendation method for augmented reality (AR) contents based on real-time user behavior model to solve the cold-start problem for new users. The experiment results demonstrate that the proposed method brings noticeable improvements in enhancing the personalized experience of the AR tour system and outperforms the conventional method in terms of recommendation performance.
Proceedings Paper
Computer Science, Artificial Intelligence
Eunhwa Song, Minju Baeck, Jihyeon Lee, Seo Young Oh, Dooyoung Kim, Woontack Woo, Jeongmi Lee, Sang Ho Yoon
Summary: We propose Memo:me, an AR sticky note app that offers priority-based color transitions and on-time reminders. The user can choose between three different colors for the color transitions or have the system automatically change the color 10 minutes before the set time. For on-time reminders, Memo:me provides visual and sound notifications at the designated time. We enable users to create virtual notes on surfaces or attach virtual notes to everyday objects. Our system aims to assist users in managing their tasks in a timely manner.
2023 IEEE CONFERENCE ON VIRTUAL REALITY AND 3D USER INTERFACES ABSTRACTS AND WORKSHOPS, VRW
(2023)
Proceedings Paper
Computer Science, Artificial Intelligence
Nicha Vanichvoranun, Bowon Kim, Dooyoung Kim, Jeongmi Lee, Sang Ho Yoon, Woontack Woo
Summary: Current works on 3D interaction mainly focus on rigid objects, with little attention given to elastic object interaction. Therefore, we propose a novel interaction method for observing and manipulating virtual fabric in a VR environment. Our method utilizes multi-sensory pseudo-haptic feedback and muscle strength data to perceive the stiffness of the fabric and flexible objects. By creating fabric patches with various stiffness levels, we demonstrate the ability to distinguish stiffness differences. This system can be implemented in a virtual cloth store to provide consumers with information about product stiffness and texture.
2023 IEEE CONFERENCE ON VIRTUAL REALITY AND 3D USER INTERFACES ABSTRACTS AND WORKSHOPS, VRW
(2023)
Proceedings Paper
Computer Science, Artificial Intelligence
Seoyoung Kang, Sungwoo Jeon, Woontack Woo
Summary: We propose a Speech-Pose integration method that addresses the limitations of existing body pose estimation. Unlike previous Speech-based gesture generation methods, our approach utilizes a vision-based system to capture the user's actual pose, with speech as a subsidiary. When the camera is out of sight, our context-aware method analyzes the speech to determine the target pose and connects it with the last captured pose using the bounding box. Our system can be a robust solution for accurate gesture delivery in avatar-mediated remote collaboration, such as VR remote yoga training.
2023 IEEE CONFERENCE ON VIRTUAL REALITY AND 3D USER INTERFACES ABSTRACTS AND WORKSHOPS, VRW
(2023)
Proceedings Paper
Computer Science, Artificial Intelligence
Sunyoung Bang, Woontack Woo
Summary: The reading experience on current AR head mounted displays is hindered by low resolution, translucency, and small field of view, especially for lengthy text. Smartphones can be used as assistive displays to improve the reading experience on AR HMDs. A user study shows that a hybrid interface with a smartphone provides a better user experience in terms of task load, comfort, visual fatigue, and perceived readability.
2023 IEEE CONFERENCE VIRTUAL REALITY AND 3D USER INTERFACES, VR
(2023)
Proceedings Paper
Computer Science, Artificial Intelligence
Hyunjin Lee, Woontack Woo
Summary: Augmented reality (AR) helps users easily accept information when they are walking by providing virtual information in front of their eyes. However, it remains unclear how to present AR notifications considering the expected user reaction to interruption. Therefore, we investigated to confirm appropriate placement methods for each type by dividing it into notification types that are handled immediately (high) or that are performed later (low). We compared two coordinate systems (display-fixed and body-fixed) and three positions (top, right, and bottom) for the notification placement. We found significant effects of notification type and placement on how notifications are perceived during the AR notification experience. Using a displayfixed coordinate system responded faster for high notification types, whereas using a body-fixed coordinate system resulted in quick walking speed for low ones. As for the position, the high types had a higher notification performance at the bottom position, but the low types had enhanced walking performance at the right position. Based on the finding of our experiment, we suggest some recommendations for the future design of AR notification while walking.
2023 IEEE CONFERENCE VIRTUAL REALITY AND 3D USER INTERFACES, VR
(2023)
Article
Computer Science, Software Engineering
Jae-eun Shin, Boram Yoon, Dooyoung Kim, Woontack Woo
Summary: This study analyzes the impact of the size, density, and layout of real indoor spaces on space-adaptive AR games, and provides design guidelines for enhancing user experiences.
IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS
(2023)
Proceedings Paper
Computer Science, Information Systems
Jae-eun Shin, Woontack Woo
Summary: This study reports on a qualitative research in which 22 participants created augmented reality stories for outdoor cultural heritage sites. By analyzing the patterns and their connection to the author's intent and creative process, the study finds that authors tend to tightly bind story arcs to confined trajectories while loosely mapping thematic content onto encompassing trajectories due to the need for spatial exploration.
PROCEEDINGS OF THE 2023 CHI CONFERENCE ON HUMAN FACTORS IN COMPUTING SYSTEMS (CHI 2023)
(2023)
Proceedings Paper
Computer Science, Information Systems
Hui-Shyong Yeo, Erwin Wu, Daehwa Kim, Juyoung Lee, Hyung-il Kim, Seo Young Oh, Luna Takagi, Woontack Woo, Hideki Koike, Aaron J. Quigley
Summary: An omni-directional camera captures the entire surrounding view, providing a complete understanding of the visual world. In OmniSense, we explore the input design space for mobile devices with such cameras and develop a working system to enable potential applications. Through technical evaluation and user study, we show the importance of the omni-directional camera in enhancing mobile interaction user experience.
PROCEEDINGS OF THE 2023 CHI CONFERENCE ON HUMAN FACTORS IN COMPUTING SYSTEMS, CHI 2023
(2023)
Proceedings Paper
Computer Science, Artificial Intelligence
Dooyoung Kim, Jinwook Kim, Jae-eun Shin, Boram Yoon, Jeongmi Lee, Woontack Woo
Summary: This paper investigates the impact of the size of virtual space and the presence of objects on the threshold range of relative translation gains. The study shows that both size and objects significantly affect the threshold range, with greater effects observed in larger spaces and spaces furnished with objects. These findings suggest that creating a perceived virtual movable space larger than the actual space and placing objects in it can enhance the effect of relative translation gains.
2022 IEEE CONFERENCE ON VIRTUAL REALITY AND 3D USER INTERFACES (VR 2022)
(2022)
