Browsing by Author "Chang, Chun-Yi"

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Dependence of the Noise Behavior on the Drain Current for Thin Film Transistors
(2014-02-01)
Tai, Ya-Hsiang
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Chang, Chun-Yi
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Hsieh, Chung-Lun
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Yang, Yung-Hsuan
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Chao, Wei-Kuang
In this letter, a noise formula is newly proposed to calculate the low frequency noise for the three kinds of amorphous silicon, low temperature polycrystalline silicon, and amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs). It is found that the noise behavior of the TFT depends on its drain current in a simple manner. Based on the analysis, the ratios of drain current to the noise level for these TFTs are compared. It reveals that a-IGZO TFT is the best candidate to be used in the active pixel sensor.
Design and Simulation of the Pixel Circuit for a 6-in Full HD LTPS TFT LCD Based on the New Digital Driving Method
(2015-04-01)
Tai, Ya-Hsiang
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Chang, Chun-Yi
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Lin, Chun-Yu
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光電工程學系
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顯示科技研究所
For all of the electronic modules in a liquid crystal display (LCD), the power consumption of data driver is only second to the backlight. Most of the power is used for converting the signal from digital to analog. In this paper, we proposed a new kind of pixel circuit with fully digital driving. As a result, the signal converting part in the conventional data driver can be omitted, and thus the power consumption can be greatly reduced. The proposed pixel circuit contains two thin-film transistors (TFTs) and a resistor in series, forming a discharging path for pixel voltage. There is also another transistor used to preset the pixel voltage. The gray level is controlled by the pulse width of the data source when the pixel is enabled by the scan voltage. The operation of the novel design is verified by simulation in the cases of a full high-definition panel. The proposed pixel circuit with the new driving method is an innovation approach to reduce data driver power consumption.
Drain Current Response to Fast Illumination Pulse for Amorphous In-Ga-Zn-O Thin-Film Transistors
(2016-12)
Tai, Ya-Hsiang
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Chang, Chun-Yi
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Chan, Po-Chun
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Dai, Jhih-Jie
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交大名義發表
In this paper, the characteristic of the amorphous indium-gallium-zinc-oxide thin-film transistors under steady bias and fast multiple-pulse illumination stress is analyzed. The change in the drain current (Delta I-D) with respect to time is measured under different light intensities and pulse frequencies. The mechanism is proposed to explain the results by correlating the oxygen vacancy (V-O) reacting with the light-induced electron-hole (e-h) pairs. The results can be well analyzed by the fitting formula and parameters for the different light pulse frequencies. The tendency proves that not all the V-O react with e-h pairs at the same reaction rate. It is observed for the first time the number of V-O with fast reaction decreases with the pulse frequency. A model is proposed to describe the relation between the number and reaction rate of V-O.
Effects of Illumination on the Noise Behavior of Amorphous Indium Gallium Zinc Oxide Thin Film Transistors
(2016-07)
Tai, Ya-Hsiang
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Chang, Chun-Yi
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Hsieh, Chung-Lun
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光電工程學系
;
顯示科技研究所
In this paper, we investigate the response of low-frequency noise to the light for the amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs). Compared with the case of nonillumination, the noise level increases with the light intensity. We find that the induced noise is more related to the drain current (I-D) with or without illumination, even though the corresponding gate voltage can be different. With fixed light intensity, the noise induced at the same I-D keeps the same regardless of the illumination history. The noise mechanism is analyzed to be mainly the carrier mobility fluctuation, but carrier number fluctuation becomes important under illumination. We speculate that oxygen vacancies generated by light affect the trapping and releasing of carrier. It thus leads to the noise increasing with illumination.
Feasibility Study of Integrating Source Driver on Array Using Low-Temperature Polycrystalline Silicon Thin-Film Transistors
(2016-12)
Tai, Ya-Hsiang
;
Lin, Ching-Chih
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Lin, Chi-Hao
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Chang, Chun-Yi
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光電工程學系
In this paper, we proposed a new kind of source driver with fully digital driving and a new approach to implement source driver on array (SoA). For the SoA circuit, the digital/analogue converters and buffers are replaced with pulse width modulation circuit and data voltage setting circuit to simplify the source driver. Thus, the signal converting part in the conventional source driver can be omitted and is much more easy to be built with thin-film transistors on the glass. Further, the feasibility of integrating SoA will be studied in the practical way. The layout area and power consumption are found to be the obstacles if we want to use the current thin-film transistor technology to implement SoA. However, the fully digital driving concept can be still applied to develop the configuration of digital interface. We can use the external source driver to produce the digital pulse width signal to set the pixel voltage. This method avoids issue of layout area and power consumption. Hence, the concept of digital interface is much more practical and feasible to reduce the cost and power of data driving instead of SoA.
Feasibility Study of Integrating Source Driver on Array Using Low-Temperature Polycrystalline Silicon Thin-Film Transistors
(2016-12)
Tai, Ya-Hsiang
;
Lin, Ching-Chih
;
Lin, Chi-Hao
;
Chang, Chun-Yi
;
光電工程學系
In this paper, we proposed a new kind of source driver with fully digital driving and a new approach to implement source driver on array (SoA). For the SoA circuit, the digital/analogue converters and buffers are replaced with pulse width modulation circuit and data voltage setting circuit to simplify the source driver. Thus, the signal converting part in the conventional source driver can be omitted and is much more easy to be built with thin-film transistors on the glass. Further, the feasibility of integrating SoA will be studied in the practical way. The layout area and power consumption are found to be the obstacles if we want to use the current thin-film transistor technology to implement SoA. However, the fully digital driving concept can be still applied to develop the configuration of digital interface. We can use the external source driver to produce the digital pulse width signal to set the pixel voltage. This method avoids issue of layout area and power consumption. Hence, the concept of digital interface is much more practical and feasible to reduce the cost and power of data driving instead of SoA.
Low-Latency Compressive Active User Identification over Frequency-Selective Fading Channels
(2018-01-01)
Chang, Chun-Yi
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Wu, Jwo-Yuh
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Yang, Ming-Hsun
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Wang, Tsang-Yi
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Shao, Shuai
This paper proposes a compressive sensing (CS) based active user identification scheme over frequency-selective fading channels. Unlike the conventional cyclic prefix (CP) based preamble transmission, our approach does not utilize CP in order to conserve signaling overhead, in turn reducing the system-wide processing latency. Our approach first estimates the multi-user channel impulse response vectors by solving a mixed l(2 )/ l(1) - norm optimization problem; then, the active users are identified via a sorting of the norms of the estimated channel vectors. By exploiting the Toeplitz channel matrix structure resulting from CP-free preamble transmission, analytic performance guarantee in term of the block restricted isometry property of the preamble matrix is given. Computer simulations are used to illustrate the performance of the proposed method.
Mechanism of Hysteresis for a-IGZO TFT Studied by Changing the Gate Voltage Waveform in Measurement
(2016-04)
Chen, Yi-Jung
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Tai, Ya-Hsiang
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Chang, Chun-Yi
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光電工程學系
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Department of Photonics
In this paper, we investigate the response time of oxygen vacancies on the hysteresis for the amorphous indium-gallium-zinc oxide thin-film transistors. The fast pulse measurement method is used to observe the drain current under the different sweeping speeds of gate voltage to clarify the mechanism of the hysteresis. Effects of light intensity and temperature are also discussed. Based on the results and the analysis, the model of oxygen vacancies is proposed to explain the effect of sweep speed on the hysteresis, which would be important for the devices to be driven in their circuit application.
Priority-Base Retransmission Scheduling for Automatic Repeat Request over Wireless Networks
(2015)
Chang, Chun-Yi
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Hsiao, Hsu-Feng
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資訊工程學系
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Department of Computer Science
When data is transmitted over error-prone channels, portions of data may be corrupted due to many reasons, including multipath fading, interference, signal attenuation, and shadowing. Even if there is only one bit uncorrectable, the data block or packet will be considered as invalid, and will be discarded. The Automatic Repeat reQuest (ARQ) is an important mechanism to recover lost packets transmitted over either unstable or congested networks. An ARQ mechanism is also implemented in the 4G wireless networks on the link layer, where a receiver can request its sender to retransmit invalid packets. However, retransmission requires additional bandwidth, and it can result in longer delay. For some applications, such as layered video streaming, the utility of each packet of a stream can be different. The QoS requirements of different flows can vary as well. In this paper, a priority-based scheduling method for retransmission is proposed for wireless channels with limited bandwidth resources. For intra-flow traffic, which can be treated as several link-layer flows, the priorities can be assigned to the flows using different QoS classes. A dynamic utility function is developed for the scheduling of invalid packets such that the overall utility can be improved. The amount of resources for retransmission is also regulated dynamically such that each flow can occupy reasonable bandwidth. The improved performance is verified with simulation results.
The Current Behaviors of the Amorphous In-Ga-Zn-O Thin-Film Transistor Under Varying Illumination Conditions
(2016-04)
Tai, Ya-Hsiang
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Chang, Chun-Yi
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Chen, Ya-Wei
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光電工程學系
;
顯示科技研究所
In this study, the time response behavior of the amorphous indium-gallium zinc-oxide (a-IGZO) thin-film transistors (TFTs) to the illumination pulse is analyzed. We modified the previously proposed fitting formula by changing the fitting parameters from constant to time dependent. The mechanism for the response behaviors is proposed based on the analysis of the fitting parameters with respect to measurement time and under different light intensities. The single-pulse measurement results and their corresponding fitting parameters is used as the database to predict the current behaviors of the TFTs under multi-pulse illumination. The predicted and measured results fit fairly well. The method to formulize the time response for the a-IGZO TFT under varying situations of illumination is thus developed, which can be important in the design and simulation of transparent electronic circuits.
The Time Response of the On-Current for the Amorphous In-Ga-Zn-O Thin Film Transistor to the Illumination Pulse
(2014)
Tai, Ya-Hsiang
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Chang, Chun-Yi
;
Chen, Ya-Wei
;
Chen, Yi-Jung
;
交大名義發表
In this study, the time response behavior of the amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) to the illumination pulse is analyzed. The mechanism is proposed to correlate the oxygen vacancy reacting with the light-induced electron-hole pairs. The temperature effect on the time response to the illumination pulse is also studied. The higher excitation level, either from light or temperature, results in the similar excited and recovering behaviors. The formulas for the time response are proposed to be possibly used in the simulation for the circuit performance in real situation of illumination, which is important in the development of transparent electronics using a-IGZO TFT. (c) The Author(s) 2014. Published by ECS. All rights reserved.