• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.314-317
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• 2000

In order to analyze the characteristics of complicated TFT-LCD (Thin Film Transistor-Liquid Crystal Display) circuits, it is indispensible to use simulation programs. In this study, we present a systematic method of extracting the input parameters of poly-Si TFT for Spice simulation. This method is applied to two different types of poly-Si TFTs fabricated in our group with good results. Among the Spice simulators, Pspice has the graphic user interface feature making the composition of complicated circuits easier. We added successfully a poly-Si TFT model on the Pspice simulator, which would contribute to efficient simulations of poly-Si TFT-LCD pixels and arrays.

• Journal of Information Display
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• v.5 no.2
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• pp.1-5
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• 2004

We developed an a-Si TFT-LCD panel with integrated gate driver circuit using a standard 5-MASK process. To minimize the effect of the a-Si TFT current and LC's capacitance variation with temperature, we developed a new a-Si TFT circuit structure and minimized coupling capacitance by changing vertical architecture above gate driver circuit. Integration of gate driver circuit on glass substrate enables single chip and 3-side free panel structure in a-Si TFT-LCD of QVGA ($240{\times}320$) resolution. And using double ASG structure the dead space of TFT-LCD panel could be further decreased.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.81-84
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• 2004

Required characteristics of poly-Si TFT's are investigated for the implementation of analog circuits to be integrated on System-on-Glass (SoG). Matching requirements on resistor values, threshold voltage and mobility of poly-Si TFT's are derived as a function of the resolution of display system. Effective mobility of poly-Si TFT's required for the realization of source driver is analyzed for various panel sizes.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.42-45
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• 2002

Small sized LTPS TFT-LCDs are developed and evaluated. Sine the fabrication process is optimized for the productivity of huge glass substrate, the pattern size is above 5${\mu}m$. The panels with integrated digital data drivers are not satisfactory to compete with a-Si technology. Therefore, LTPS panels are implemented by PMOS technology and it is proved that they can be competitive with a-Si TFT-LCDs in terms of performance and cost.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.395-398
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• 2004

We developed an a-Si TFT-LCD panel with integrated gate driver circuit using a standard 5-MASK process. To minimize the effect of the a-Si TFT current and LC's capacitance variation with temperature, we developed a new a-Si TFT circuit structure and minimized coupling capacitance by changing vertical architecture above gate driver circuit. Integration of gate driver circuit on glass substrate enables single chip and 3-side free panel structure in a-Si TFT-LCD of QVGA(240$^{\ast}$320) resolution. And using double ASG structure the dead space of TFT-LCD panel could be further decreased.

• ETRI Journal
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• v.34 no.4
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• pp.633-636
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• 2012

A dynamic analysis of an amorphous silicon (a-Si) thin film transistor liquid crystal display (TFT-LCD) pixel is presented using new a-Si TFT and liquid crystal (LC) capacitance models for a Simulation Program with Integrated Circuit Emphasis (SPICE) simulator. This dynamic analysis will be useful when predicting the performance of LCDs. The a-Si TFT model is developed to accurately estimate a-Si TFT characteristics of a bias-dependent gate to source and gate to drain capacitance. Moreover, the LC capacitance model is developed using a simplified diode circuit model. It is possible to accurately predict TFT-LCD characteristics such as flicker phenomena when implementing the proposed simulation model.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.205-207
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• 2008

The new process for hybrid silicon thin film transistor (TFT) using DPSS laser has been developed for realizing both low-temperature poly-Si (LTPS) TFT and a-Si:H TFT on the same substrate as a backplane of active matrix liquid crystal display. LTPS TFTs are integrated on the peripheral area of the panel for gate driver integrated circuit and a-Si:H TFTs are used as a switching device for pixel in the active area. The technology has been developed based on the current a-Si:H TFT fabrication process without introducing ion-doping and activation process and the field effect mobility of $4{\sim}5\;cm^2/V{\cdot}s$ and $0.5\;cm^2/V{\cdot}s$ for each TFT was obtained. The low power consumption, high reliability, and low photosensitivity are realized compared with amorphous silicon gate driver circuit and are demonstrated on the 14.1 inch WXGA+ ($1440{\times}900$) LCD Panel.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.249-256
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• 2007

AIn this paper, a new desist of LDI controller IC for general purpose is proposed for driving the LDI(LCD Driver Interface) controller in $4{\sim}9$ inches sized portable small-medium TFT-LCD(Thin Film Transistor addressed -Liquid Crystal Display) panel module. The designed LDI controller was verified on the FPGA(Reld Programmable Gate Array) test board, and was made the interactive operation with the commercial TFT-LCD panel successfully. The purpose of design is that it is standardized the LDI controller's operation by one LDI controller for driving all TFT-LCD panel without classifying the panel vendor, and size. The main advantage for new general-purpose LDI controller is the usage for the desist of all panel's SoG(System on a Glass) module because of the design for the standard operation. And in the previous method, it used each LDI controller for every LCD vendor, and panel size, but because a new one can drive all portable small-medium sized panel, it results in reduction of LDI controller supply price, and manufacturing cost of AV(Audio Video) board and panel. In the near future, the development of SoG IC(Integrated Circuit) for manufacturing more excellent functional TFT-LCD panel module is necessary. As a result of this research, the TFT-LCD panel can make more small size, and light weight, and it results in an upturn of domestic company's share in the world market. With the suggested theory in this paper, it expects to be made use of a basic data for developing and manufacturing for the SoG chip of TFT-LCD panel module.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2061-2062
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• 2006

a-Si(amorphous silicon) TFT(thin film transistor)는 TFT-LCD(liquid crystal display)의 화소 스위칭(switching) 소자로 폭넓게 이용되고 있다. 현재는 a-Si을 이용하여 gate drive IC를 기판에 집적하는 ASG(amorphous silicon gate) 기술이 연구, 적용되고 있는데 이때 가장 큰 제약은 문턱 전압(Vth)의 이동이다. 특히 고온에서는 문턱 전압의(Vth) 이동이 가속화 되고, Ioff current가 증가 하게 되고, 저온($0^{\circ}C$)에서는 전류 구동능력이 상온($25^{\circ}C$) 상태에서 같은 게이트 전압(Vg)에 대해서 50% 수준으로 감소하게 된다. 특히 ASG 회로는 여러 개의 TFT로 구성되는데, 각각의 TFT가 고온에서 Vth shift 값이 다르게 되어 설계시 예상하지 못 한 고온에서의 화면 무너짐 현상 즉 고온 노이즈 불량이 발생 할 수 있다. 고온 노이즈 불량은 고온에서의 각 TFT의 문턱전압 및 $I_D-V_G$ 특성을 측정한 결과 고온 노이즈 불량에 영향을 주는 인자가 TFT의 width와 기생 capacitor비 hold TFT width가 영향을 주는 것으로 실험 및 시뮬레이션 결과 확인이 되었다. 발생 mechanism은 ASG 회로는 AC 구동을 하기 때문에 Voff 전위에 ripple이 발생 되는데 특히 고온에서 ripple이 크게 증가 하여 출력 signal에 영향을 주어 불량이 발생하는 것을 규명하였다.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.172-175
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• 2005

a-Si TFT는 TFT-LCD의 화소 스위칭(swiching) 소자로 폭넓게 이용되고 있다. 현재는 a-Si을 이용하여 gate drive IC를 기판에 집적하는 기술이 연구, 적용되고 있는데 이때 가장 큰 제약은 문턱 전압의 이동이다. 펄스(pulse)형태로 인가되는 gate 전압에 의한 문턱 전압 이동은 a-Si:H gate에 인가되는 펄스의 크기, duty cycle, drain pulse의 크기 및 동작 온도에 기인하며 실험결과를 통해 입증된다. 초기의 DC Stress 측정 Data를 이용하여 문턱전압이동을 모델링/시뮬레이션한 결과 a-Si:H gate 회로설계 및 펄스 조건에 따라 stress시간에 따른 gate의 출력 파형 예측이 가능하고 상온에서 Von=21V를 인가한 결과, 약 4년후에서 시프트레지스터 출력 파형이 열화되기 시작한다.