• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.6
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• pp.31-38
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• 2009

To improve the image quality and lower the power consumption of the mobile applications, it is the one of the best candidate to control the backlight unit of the LCD module with ambient light. Ambient light sensor and readout circuit were integrated in LCD panel for the mobile applications, and we designed them with LTPS TFT. We proposed noble start-up correction in order to correct the variation of the photo sensors in each panel. We used time-to-digital method for converting photo current to digital data. To effectively merge time-to-digital method with start-up correction, we proposed noble dual slope correction method. The entire readout circuit was designed and estimated with LTPS TFT process. The readout circuit has very simple and stable structure and timing, so it is suitable for LTPS TFT process. The readout circuit can correct the variation of the photo sensors without an additional equipment, and it outputs the 4-levels digital data per decade for input luminance that has a dynamic range of 60dB. The readout rate is 100 times/sec, and the linearity error for digital conversion is less than 18%.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1340-1343
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• 2007

We have simultaneously fabricated LTPS TFTs and integrated photodiodes on the same glass substrates without any additional LTPS process. The structure of an integrated photodiode is a lateral p-i-n diode with a gate. The performances of a photodiode were improved at a negative gate voltage.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.903-906
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• 2008

We developed the advanced LTPS (A-LTPS) manufacturing process. The a-Si TFT process was combined with selectively enlarging laser crystallization (SELAX) technology to improve the carrier mobility in the region where the peripheral circuits are to be fabricated. A 2.4-inch IPS-pro LCD panel for personal digital assistant use was successfully fabricated using the developed technology.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.46-49
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• 2002

Recent trends of low-temperature polycrystalline Si (LTPS) TFT technologies are presented. Characteristics of LTPS TFT processes are compared with those of a-Si TFT's. In order to compete with well-established a-Si TFT-LCD technology, LTPS process has to be as simple as possible. One of the most critical processes, recrystallization of a-Si thin films, could be the process for the differentiation of LTPS technology. Along with these technical reviews, a recent development of the 5.0-inch LTPS TFT-LCD is presented. In order to achieve high-performance display characteristics and save the power consumption, the transflective mode is adopted. The 5.0-inch display with 186 pixel-per-inch, high-resolution LCD was measured to be 10% for the reflectance and 70:1 for the contrast ratio. This display is designed for a high information content hand-held PC (HHPC) application.

• Journal of Information Display
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• v.9 no.3
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• pp.1-7
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• 2008

With the aim of creating a high-quality display system with value-added functions, we designed a current mode multiplexer for LTPS TFT devices. The multiplexers had less than 1 volt logic swing, and speed improvement was evident compared with that of conventional CMOS architecture. We refined the multiplexer to achieve a more stable current steering operation. By using the versatility of the multiplexer, a new NAND/AND and NOR/OR logic gates were designed through the simple modification of signal connections. Two micron LTPS TFT parameters were used during the HSPICE simulation of the circuits.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1261-1262
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• 2008

Laser-based crystallization techniques are ideally-suited for forming high-quality crystalline Si films on active-matrix display backplanes, because the highly-localized energy deposition allows for transformation of the as-deposited a-Si without damaging high-temperature-intolerant glass and plastic substrates. However, certain significant and non-trivial attributes must be satisfied for a particular method and implementation to be considered manufacturing-worthy. The crystallization process step must yield a Si microstructure that permits fabrication of thin-film transistors with sufficient uniformity and performance for the intended application and, the realization and implementation of the method must meet specific requirements of viability, robustness and economy in order to be accepted in mass production environments. In recent years, Low Temperature Polycrystalline Silicon (LTPS) has demonstrated its advantages through successful implementation in the application spaces that include highly-integrated active-matrix liquid-crystal displays (AMLCDs), cost competitive AMLCDs, and most recently, active-matrix organic light-emitting diode displays (AMOLEDs). In the mobile display market segment, LTPS continues to gain market share, as consumers demand mobile devices with higher display performance, longer battery life and reduced form factor. LTPS-based mobile displays have clearly demonstrated significant advantages in this regard. While the benefits of LTPS for mobile phones are well recognized, other mobile electronic applications such as portable multimedia players, tablet computers, ultra-mobile personal computers and notebook computers also stand to benefit from the performance and potential cost advantages offered by LTPS. Recently, significant efforts have been made to enable robust and cost-effective LTPS backplane manufacturing for AMOLED displays. The majority of the technical focus has been placed on ensuring the formation of extremely uniform poly-Si films. Although current commercially available AMOLED displays are aimed primarily at mobile applications, it is expected that continued development of the technology will soon lead to larger display sizes. Since LTPS backplanes are essentially required for AMOLED displays, LTPS manufacturing technology must be ready to scale the high degree of uniformity beyond the small and medium displays sizes. It is imperative for the manufacturers of LTPS crystallization equipment to ensure that the widespread adoption of the technology is not hindered by limitations of performance, uniformity or display size. In our presentation, we plan to present the state of the art in light sources and beam delivery systems used in high-volume manufacturing laser crystallization equipment. We will show that excimer-laser-based crystallization technologies are currently meeting the stringent requirements of AMOLED display fabrication, and are well positioned to meet the future demands for manufacturing these displays as well.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1029-1032
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• 2005

A 262K-color QVGA LTPS AMLCD was developed. This panel has integrated gate driver and data multiplexer (1:3) by p_Si LTPS TFT process. The commercialized driver IC was adopted to implement this display. Fine image quality, low powerconsumption and cost-efficiency feature make the panel be suitable for mobile application.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.413-418
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• 2006

Highly stable thin-film transistor (TFT) pixel employing both low temperature polycrystalline silicon (LTPS) and amorphous silicon (a-Si) for active matrix organic light emitting diode (AMOLED) is discussed. ELA (excimer laser annealing) LTPS-TFT pixel should compensate $I_{OLED}$ variation caused by the non-uniformity of LTPS-TFT due to the fluctuation of excimer laser energy and amorphous silicon TFT pixel is desired to suppress the decrease of $I_{OLED}$ induced by the degradation of a-Si TFT. We discuss various compensation schemes of both LTPS and a-Si TFT employing the voltage and the current programming.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.685-688
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• 2008

Mini-LVDS has been widely used for high speed data transmission because it provides low EMI and high bandwidth for display driver. In this paper, a Mini-LVDS output buffer with LTPS TFT process is presented which provides sufficient performance in the presence of large variation in the threshold voltage and mobility and kink effect.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.417-420
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• 2007

A 12k-bit SRAM has been developed for line memory of system-on-glass (SoG) with lowtemperature poly-silicon (LTPS) thin film transistor (TFT). For accurate sensing even with the large variation and mismatches in the characteristics of LTPS TFT, mismatch immune sense amplifier is developed. The SRAM shows 30ns read access time with 7V supply voltage while dissipating 4.05mW and 1.75mW for write and read operation, respectively