Browsing by Author "Lin, Wei-Ting"

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A 20MHz Low Dropout Controlled Current Sensor for Constant On-Time Based Envelop Tacking Supply Modulator for Radio Frequency Power Amplifier
(2018-01-01)
Lin, Wei-Ting
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Lin, Zong-Yi
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Liu, Chia-Hao
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Chen, Ke-Horng
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Lin, Ying-Hsi
this paper presents a LDO-controlled current sensor for accelerating constant on-time (COT) switching regulators (SWRs) for high efficiency envelope tracking power modulators (ETSMs) for RF power amplifiers (RF PAs). The proposed LDO-controlled current sensor controls the feedback loop of the SWR, rather than the traditional current sensing technique, in the case of fast envelope tracking. The LDO regulator behaves as the master to rapidly trigger the SWR as a slave energy provider to rapidly deliver the average energy to the RF PA for high efficiency. The experimental results show that the test chip fabricated in 0.18 mu m CMOS process can accurately track the RF envelope signal, and the peak efficiency is 86.7% when the power is 0.95W.
A Constant-on-Time Control DC-DC Buck Converter With the Pseudowave Tracking Technique for Regulation Accuracy and Load Transient Enhancement
(2018-07-01)
Yang, Wen-Hau
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Huang, Chao-Jen
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Huang, Han-Hsiang
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Lin, Wei-Ting
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Chen, Ke-Horng
Constant-on-time (COT) control with an additional current feedback path in conventional buck converters can remove the need of large equivalent series resistance (ESR) at the output capacitor but it induces degraded output voltage regulation accuracy and slow transient response owing to opposite reaction between the output voltage and the additional current feedback information. Therefore, this paper proposes the pseudowave tracking (PWT) technique to reduce the load-dependent dc offset voltage of output load regulation while keeping the fast transient response similar to conventional COT buck converter with large ESR. The PWT technique further improves the transient response instantly by extending on-time and off-time periods during light-to-heavy and heavy-to-light load changes, respectively. The test chip fabricated in 28 nm CMOS process has demonstrated the improvement of offset voltage from 42 to 4 mV, while the transient response can be improved to 4 and 5 mu s with load changes from 0.3 to 1.7 A and vice versa, respectively.
Analyzing determinants for promoting emerging technology through intermediaries by using a DANP-based MCDA framework
(2018-06-01)
Chen, Shih-Hsin
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Lin, Wei-Ting
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教育研究所
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科技管理研究所
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Institute of Education
Multiple Criteria Decision Analysis (MCDA) has been widely considered a useful tool for evaluating decision making. Several derivatives of MCDA, including AHP, ANP, DANP, have been implemented in previous studies to construct real-world applications. However, literature combining a systematic introduction on methodological developments of MCDA with an empirical implementation in promoting technology through intermediaries is still rare. To fill in this gap, this paper begins with introducing the methodological development of MCDA to set out an analytical framework, namely DANP for the empirical analysis. Consequently, this paper applied DANP to analyze multiple determinants and five dimensions that we summarized from existing literature to find out the key determinants and the interdependent relationship for promoting the emerging sector through institutional intermediaries. While conducting empirical implementation, 33 experts from major intermediaries involved in promoting the biotechnology sector were visited. 7 out of 33 of these experts were further visited for interview to verify our analysis. Based on our MCDA analysis, we found that government policies and regulations are the most influential determinates while promoting emerging sectors through intermediaries. This paper contributes to the literature in several ways including highlighting methodological improvements of DANP, improving approaches on empirical data collection, and implementing an empirical MCDA analysis by applying an influential network relation map (INRM) to construct useful policy suggestions for real-world applications.
Dependence of the structure and orientation of VSS grown Si nanowires on an epitaxy process
(2019-08-07)
Chiang, Yi-Ting
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Chou, Yi
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Huang, Chang-Hsun
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Lin, Wei-Ting
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Chou, Yi-Chia
We investigated the vapor-solid-solid growth of Si nanowires from Ni silicides on Si(111), Si(110), and GaN substrates. The morphology and structures of Si on these substrates are distinct, and are dependent on substrate lattices and an epitaxy process during growth. The sidewall facets and epitaxy of silicides and Si were discussed. In addition, Si grown on GaN nanowires was investigated which led to the formation of branched nanowire structures. The Si nanowires/nanodots lie on the surface of GaN nanowires to maintain lower system energy. We manipulated the whole process in a UHV and studied the crystal growth of Si on different lattice substrates. Meanwhile, the process which occurred in a non-UHV led to less regularity on the NiSi2 crystal facets and interface epitaxy between NiSi2 and Si nanowires.
Improvements in the reliability of a-InGaZnO thin-film transistors with triple stacked gate insulator in flexible electronics applications
(2015-11-30)
Chen, Hua-Mao
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Chang, Ting-Chang
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Tai, Ya-Hsiang
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Chen, Kuan-Fu
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Chiang, Hsiao-Cheng
This study examined the impact of the low-temperature stacking gate insulator on the gate bias instability of a-InGaZnO thin film transistors in flexible electronics applications. Although the quality of SiNx at low process/deposition temperature is better than that of SiOx at similarly low process/deposition temperature, there is still a very large positive threshold voltage (V-th) shift of 9.4 V for devices with a single low-temperature SiNx gate insulator under positive gate bias stress. However, a suitable oxide-nitride-oxide-stacked gate insulator exhibits a Vth shift of only 0.23 V. This improvement results from the larger band offset and suitable gate insulator thickness that can effectively suppress carrier trapping behavior. (C) 2015 Elsevier B.V. All rights reserved.
Magnification Enhanced Multi-Aperture System with Distorted Lens Design
(2017-01-01)
Liu, Yueh-Sheng
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Lin, Wei-Ting
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Chen, Chun-Ho
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Huang, Yi-Pai
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光電工程學系
In recent years, some companies take a dual-camera system to improve the magnification ability and zoomed image's quality in multi-function imaging devices. The solution comprises two apertures to perform a large zooming range without any mechanism moving optical elements: one with a wide-angle lens for lower magnification and the other with a telephoto lens for higher magnification. Nevertheless, this dual-camera system still needs to interpolate the digital zoomed image between the lower and higher magnification images results in a discontinuous quality of zoomed image. We propose a distorted lens (DL) dual-camera system with varying focal length for higher magnification performance and smoother optical zoom. The proposed optical system has a greater pixel count per field angle at the center of sensor than at the periphery of sensor. Therefore, we sacrifice some resolution of the peripheral FOV to enhance the resolution of the center FOV for improving the capability of magnification. For instance, using a 20 MP sensor and displaying a Full HD zoomed image, the maximum magnification factor of 7.54 is achieved in our distorted lens system, but this factor of 3.12 in the distortionless lens system. In other words, we raise the capability of magnification up to 242%.
Organic solar cells comprising multiple-device stacked structures exhibiting complementary absorption behavior
(2014-01-01)
Lin, Wei-Ting
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Lin, Yen-Tseng
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Chou, Chu-Hsien
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Chen, Fang-Chung
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Hsu, Chain-Shu
We developed organic solar cells based on multiple-device stacked structures featuring complementary absorption behavior. The first, semitransparent (ST) subcell featured an inverted structure; its anode comprised a MoO3/Ag bilayer. This structure provided a transmittance of greater than 35% in the visible region. The second subcell, featuring a low-band-gap small molecule in its photoactive layer, was stacked onto the ST device; the two subcells could be connected either in series or in parallel. Because the two subcells exhibited complementary absorption behavior, their stacked structure connected in parallel displayed a power conversion efficiency of 4.37%, greater than those of the isolated subcells. (C) 2013 Elsevier B.V. All rights reserved.
Polymorphism Control of Layered MoTe2 through Two-Dimensional Solid-Phase Crystallization
(2019-06-19)
Huang, Jyun-Hong
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Hsu, Hao-Hua
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Wang, Ding
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Lin, Wei-Ting
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Cheng, Chun-Cheng
Two-dimensional (2D) molybdenum ditelluride (MoTe2) exhibits an intriguing polymorphic nature, showing stable semiconducting 2H and metallic 1T' phases at room temperature. Polymorphism in MoTe2 presents new opportunities in developing phase-change memory, high- performance transistors, and spintronic devices. However, it also poses challenges in synthesizing homogeneous MoTe2 with a precisely controlled phase. Recently, a new yet simple method using sputtering and 2D solid-phase crystallization (SPC) is proposed for synthesizing high-quality and large-area MoTe2. This study investigates the polymorphism control of MoTe2 synthesis using 2D SPC. The Te/Mo ratio and oxygen content in the as-sputtered films correlate strongly with the final phase and electrical properties of SPC MoTe2. Furthermore, the SPC thermal budget may be exploited for stabilizing a deterministic phase. The comprehensive experiments presented in this work demonstrate the versatile and precise controllability on the MoTe2 phase by using the simple 2D SPC technique.
Relative carrier-envelope phase stabilization of hybridly synchronized ultrafast Yb and Er fiber-laser systems with the feed-forward scheme
(2015-03-15)
Fong, Bo-Jyun
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Lin, Wei-Ting
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Wu, Shang-Ying
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Peng, Jin-Long
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Hsiang, Wei-Wei
Stabilization of the relative carrier-envelope (CE) phase for hybridly synchronized two-color fs Yb and Er fiber-laser systems is demonstrated for the first time by utilizing the feed-forward scheme based on an acousto-optic frequency shifter. The slow drift issues arising from the feed-forward scheme are solved by adding the in-loop relative CE frequency coarse stabilization via modulating the laser pump current. Sub-fs timing locking between the two-color pulses is still maintained due to the fast response and large locking range of hybrid synchronization. The approach provides an alternative way to obtain phase-stable synchronized two-color pulses with higher pulse energies. (C) 2015 Optical Society of America
Stabilizing the relative carrier-envelop phase of hybridly synchronized ultrafast Yb and Er fiber laser systems by the feed-forward scheme
(2015)
Hsiang, Wei-Wei
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Fong, Bo-Jyun
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Lin, Wei-Ting
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Wu, Shang-Ying
;
Peng, Jin-Long
Stabilization of the relative carrier-envelope (CE) phase for hybridly synchronized two-color fs Yb and Er fiber laser systems is demonstrated for the first time by utilizing the feed-forward scheme based on an acousto-optic frequency shifter.
The dynamic role of universities in developing an emerging sector: a case study of the biotechnology sector
(2017-10-01)
Chen, Shih-Hsin
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Lin, Wei-Ting
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教育研究所
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科技管理研究所
;
Institute of Education
Literature maintains that the role of universities has shifted from pure knowledge dissemination organisations into the key intermediaries of technology commercialisation, especially in the case of the developing emerging high-tech sector (Etzkowitz, Webster, Gebhardt, & Terra, 2000; Vallas & Kleinman, 2008). To further explore the dynamic role of the universities interacting with the other actors in the innovation system, this paper examines the changing roles of the universities that have actively interacted with the biotechnology industry in Taiwan from 2000 to 2012. Combining social network analysis and interview data on a longitudinal dataset gathered from 125 IPO biotechnology firms, this paper aims to explore the R&D collaboration networks between the universities and the other actors in the biotechnology sectoral innovation system to understand how universities make use of knowledge exchanged with other parties to shape society while developing emerging industries. The involvement rate of academia in the knowledge transfer networks appears to have increased since 2000 but more can be done to spur scalable action after 2008, and therefore association with other similar evolving areas. Moreover, the participation of foreign collaboration is one which needs some attention. The finding of this paper sheds light on the changing role of academia in developing emerging technologies in technology followers, while the innovation ecosystem is ready for academia-industry collaboration, universities not only take charge of disseminating knowledge but also serve as the major intermediaries in the process of commercialising science and technologies developed through the universities. Future policies may need to boost more partaking between the universities and industries by motivating the transmission of knowledge capital through encouraging technology commercialisation in academia. (C) 2016 Elsevier Inc. All rights reserved.