A novel data serializer is proposed for use in mobile TFT-LCD driver ICs. The proposed data serializer adopting hierarchical switching and repeater/separator schemes provides 82% power reduction and 27% speed improvement with 27% area saving. Measured overall power consumption of a TFT-LCD driver IC with the proposed data serializer was reduced by as much as 49%.

Oxide material can make transparent devices with transparent electrodes. We developed a transparent oscillator and rectifier circuits with oxide TFTs. The source/drain and gate electrodes were made by indium thin oxide (ITO), and active layer made by transparent material of IGZO (Indium Gallium Zinc Oxide) on a glass substrate. The RC oscillator was composed of bootstrapped inverters, and 813 kHz oscillation frequency was accomplished at VDD = 15 V. For DC voltage generation from RF, transparent rectifier was fabricated and evaluated. This DC voltage from rectifier powered to the oscillator which operated successfully to create RF. For data transmission, RF transmission was evaluated with RF from the transparent oscillator. An antenna was connected to the oscillator and RF transmission to a receiving antenna was verified. Through this transmission antenna, RF was transmitted to a receiving antenna successfully. For transparent system of RFID, transparent antenna was developed and verified sending and receiving of data.

Opto-Thermal analysis of Semiconductor Blue-Multi-Laser-Diode Annealing (BLDA) for amorphous Si (a-Si) film is conducted by varying the irradiation power, the scanning velocity and the beam shape of blue-laser of 445 nm. Thermal profiles, maximum temperature of the a-Si film and the melting duration are evaluated. By comparing the simulated results with the experimental results, the excellent controllability of BLDA for arbitrary grain size can be explained consistently by the relation between irradiation time and melting duration. The results are useful to estimate poly-crystallized phase such as micro-polycrystalline Si, polycrystalline Si and anisotropic lateral growth of single-crystal-like Si.

The electrical properties of poly-Si thin film transistors (TFTs) using rapid thermal annealing with various gate oxide thicknesses were studied in this work. It was found that Poly-Si TFT electrical characteristics with the thinnest gate oxide thickness after RTA treatment exhibits the largest performance improvement compared to TFT with thick oxide as a result of the increased incorporated amounts of the nitrogen and oxygen. Thus, the combined effects can maintain the advantages and avoid the disadvantages of scaled-down oxide, which is suitable for small-to-medium display mass production.

Conventional radar imaging systems use Fourier transform for image formation, but due to the target's complicated motion the Doppler spectrum is time-varying and thus the reconstructed image becomes blurred even after applying standard motion compensation algorithms. Therefore, sophisticated algorithms such as polar reformatting are usually employed to produce clear images. Alternatively, Joint Time-Frequency (JTF) analysis can be used for image formation which produces clear image without using polar reformatting algorithm. In this paper, a new JTF-based method is proposed for image formation in inverse synthetic aperture radars (ISAR). This method uses minimum entropy criterion for optimum parameter adjustment of JTF algorithms. Short Time Fourier Transform (STFT) and Fractional Fourier Transform (FrFT) are applied as JTF for time-varying Doppler spectrum analysis. Both the width of Gaussian window of STFT and the order of FrFT, α, are adjusted using minimum entropy as local and total measures. Furthermore, a new statistical parameter, called normalized correlation, is defined for comparison of images reconstructed by different methods. Simulation results show that α-order FrFT with local adjustment has much better performance than the other methods in this category even in low SNR.

Slit-Mura defect is a notorious yield flaw of color filters. In this study, an innovative non-contact in-line optical inspection method is developed to detect low contrast slit Mura through quantitative measurements by a spectrometer. Using the features of either thickness or chromaticity profiles across a slit Mura, a thickness difference from 21 nm to 41 nm of color filters can be differentiated accurately. Thus, the quality of color filters can be accessed in-line during the manufacturing process TFT-LCDs.

The polycrystalline silicon (poly-Si) TFT has two insulator interfaces between the polycrystalline silicon and front and back insulators. These interfaces have trap states, which affect the characteristics of poly-Si TFT. In the silicon-on-insulator (SOI) technology area, using the dual-gated, fully-depleted SOI MOSFET under the depleted back-channel condition, the back-interface trap density can be calculated through the front-channel threshold voltage and film thicknesses. The front-interface trap density is also evaluated changing the roles of both gates. This evaluation method for front- and back- interface trap densities is called the threshold-voltage method. To apply this threshold-voltage method to the "medium-thickness" poly-Si TFT, of which the channel is not fully depleted in normal single gate bias operation, the biases for both front and back gates are controlled to realize full depletion. Under the fully-depleted condition, the front- or back- threshold voltage of poly-Si TFT is carefully extracted by the second-derivative method changing back- and front- gate biases. We evaluated the front- and back- interface trap densities not only for normal operation but also under stress. To evaluate the bias and temperature stress effect, we used two types of samples, which are made by different processes. The evaluated front- and back- interface trap densities for both samples in initial state are around 51011 to 1.31012 cm-2eV-1, which are almost the same as the reported values. Applying bias and temperature stress shows the variation of these interface-trap densities. Samples with large shifts of the front-channel threshold voltage show large trap density variation. On the other hand, samples with small threshold voltage shifts show small trap density variation. The variation of the back-interface trap density during the stress application showed a correlation to the front-channel threshold voltage shift.

The TFT-LCD image has non-uniform brightness that is the major difficulty of finding the visible defect called Mura in the field. To facilitate Mura detection, background signal shading should level off and Mura signal must be amplified. In this paper, Mura signal amplification and background signal flattening method is proposed based on human visual system (HVS). The proposed DC normalized contrast sensitivity function (CSF) is used for the Mura signal amplification and polynomial regression (PR) is used to level off the background signal. In the enhanced image, tri-modal thresholding segmentation technique is used for finding Dark and White Mura at the same time. To select reliable defect, falsely detected invisible region is eliminated based on Weber's Law. By the experimental results of artificially generated 1-d signal and TFT-LCD image, proposed algorithm has novel enhancement results and can be applied to real automated inspection system.

A cross-coupled charge pump with internal pumping capacitor, which is advantageous from a point of minimizing TFT-LCD driver IC module, is newly proposed in this paper. By using NMOS and PMOS diodes connected to boosting nodes from VIN nodes, the pumping node is precharged to the same value at the pumping node in starting pumping. Since the first-stage charge pump is designed differently from the other stage pumps, a back current of pumped charge from charge pumping node to input stage is prevented. As a pumping clock driver is located in front of pumping capacitor, the driving capacity is improved by reducing a voltage drop of the pumping clock line from parasitic resistor. Finally, a layout area is decreased more compared with the conventional cross-coupled charge pump by using a stack-MIM capacitor. A proposed charge pump for TFT-LCD driver IC is designed with 0.13 µm triple-well DDI process, fabricated, and tested.

This paper presents an asynchronous design technique, an enabler for the emerging technology of flexible microelectronics that feature low-temperature processed polysilicon (LTPS) thin-film transistors (TFT) and surface-free technology by laser annealing/ablation (SUFTLA®). The first design instance chosen is an 8-bit microprocessor. LTPS TFTs are good for realizing displays having integrated VLSI circuit at lower costs. However, LTPS TFTs have drawbacks, including substantial deviations in characteristics and the self-heating phenomenon. To solve these problems, the authors adopted the asynchronous circuit design technique and developed an asynchronous design language called Verilog+, which is based on a subset of Verilog HDL® and includes minimal primitives used for describing the communications between modules, and the dedicated tools including a translator called xlator and a synthesizer called ctrlsyn. The flexible 8-bit microprocessor stably operates at 500 kHz, drawing 180 µA from a 5 V power source. The microprocessor's electromagnetic emissions are 21 dB less than those of the synchronous counterpart.

The thin film transistor liquid crystal display (TFT-LCD) image has nonuniform brightness, which is a major difficulty in finding the Mura defect region. To facilitate Mura segmentation, globally widely varying background signal must be flattened and then Mura signal must be enhanced. In this paper, Mura signal enhancement and background-signal-flattening methods using wavelet coefficient processing are proposed. The wavelet approximation coefficients are used for background-signal flattening, while wavelet detail coefficients are employed to magnify the Mura signal on the basis of an adapted contrast sensitivity function (CSF). Then, for the enhanced image, trimodal thresholding segmentation technique and a false-region elimination method based on the human visual system (HVS) are employed for reliable Mura segmentation. The experimental results show that the proposed algorithms produce promising results and can be applied to automated inspection systems for finding Muras in a TFT-LCD image.

We propose a filtering method for optimal estimation of TFT-LCD's surface region except defect's region. To estimate the non-uniform intensity variation on TFT-LCD surface region, the 4-directional Gaussian filter based on image pyramid structure is proposed. The experimental result verified the proposed method's performance

A novel driving concept, "pulse-width modulation with current uniformization," is proposed for thin-film transistor driven organic light-emitting diode displays (TFT-OLEDs). An example of this driving concept is the combination of "pulse-width modulation with a self-biased inverter" and a "time-ratio grayscale with current uniformization." Its driving operation is confirmed by circuit simulation. It is found that this driving method can compensate the characteristic deviations and degradations of both TFTs and OLEDs and immensely improve luminance uniformity. Finally, its driving operation is also confirmed by an actual pixel equivalent circuit.

A two-dimensional (2-D) physical model of n-channel poly-Si LDD TFTs in comparison with that of SD TFTs is presented to analyze hot-carrier degradation. The model is based on 2-D device simulator's Gaussian doping profiles for the source and drain junctions fitted to the lateral and vertical impurity profiles in poly-Si obtained from a 2-D process simulator. We have shown that, in the current saturation bias (Vg

In this paper, a high-speed logic circuitry using bootstrapped and low-temperature polysilicon (LTPS) technologies for TFT-LCD panels is proposed. The new circuitry realizes high-speed operation owing to the application of a logic-swing voltage that is wider than the power-supply voltage using bootstrapped technology. As a result, the new logic circuitry can be operated at an operational frequency around 3-10 times higher than that of the conventional circuitry under the conditions of a 0.5 pF load capacitor at the output of a noninverting buffer and +10 V power-supply voltages. The new circuit is named "BST-TFT logic circuitry."

We present our recent results of the 10-bit data driver LSI for 42-inch diagonal TFT-LCD TV with full HD format. To develop data driver LSIs for a true 10-bit TFT-LCD TV with full HD (19201080) format, small chip area, low power consumption, and output uniformity between channels are key problems that must be solved. By applying a two-stage DAC which combines 8-bit resistor-string DAC and 2-bit binary weighted capacitor DAC, the area increase is limited to only 30% compared to the area of 8-bit resistor-string DAC. The output deviation between channels is successfully limited within 5 mV and the driver LSI with 414 outputs consumes the maximum total current of 16 mA when driving 42-inch HDTV panel. We confirmed that the picture with 10-bit shades of gray is much more natural than that with 8-bit shades of gray.

A blind symbol synchronization scheme for MIMO and Multi-User OFDM systems is proposed, which utilizes short-time Fourier Transformation (STFT) to obtain 2D (time and frequency) timing information from the received signals. By analyzing the obtained 2D time-frequency amplitude spectrum, intervals where no inter-symbol interference (ISI) exists are checked out for symbol synchronization, and samples during these intervals are used to carry out carrier frequency offset estimation. Theoretical analysis and simulation results show that the proposed method is more robust and provides more accurate carrier frequency offset estimation than traditional schemes.

Driving methods for TFT-OLEDs are explained with their features and classified from the viewpoints of grayscale methods and uniformizing methods. This classification leads us to a novel proposal using time ratio grayscale and current uniformization. This driving method maintains current uniformity and simultaneously overcomes charging shortage of the pixel circuit for low grayscale levels and current variation due to the shift of operating points. Tolerance toward degraded characteristics, linearity of grayscale and luminance uniformity against degraded characteristics are confirmed using circuit simulation.

Poly-Si TFT (Thin Film transistor) fabricated below 170 using excimer laser crystallization of sputtered Si films was characterized. In particular, a gate insulator with a breakdown field exceeding 8 MV/cm was deposited by using ICP (Inductively Coupled Plasma) CVD (Chemical Vapor Deposition). A buffer layer possessing high thermal conductivity was inserted between the active channel and the plastic substrate, in order to protect the plastic substrate from the thermal energy of the laser and to increase adhesion of Si film on plastic. Using this method, we successfully fabricate TFT with a stable electron field-effect mobility value greater than 14.7 cm2/Vsec.

The role of electric field in metal-induced lateral crystallization (MILC) of amorphous Si (a-Si) under limited Ni-supply condition has been investigated. The nominal lateral-growth rate was increased from 3.6 µm/h (no-electric field) to 23 µm/h at the positive electrode side and reduced to 2.8 µm/h at the negative electrode side in presence of the electric field of 20 V/cm. However, spontaneously nucleated needle-like Si crystals were observed in the enhanced positive electrode side, which have been found to be independent of the MILC. Further investigation under the condition where Ni in the supply region was removed on the way of crystallization revealed that the electric field enhanced crystallization greatly reduced. These results indicate that the electric field does not enhance the MILC growth but enhances the diffusion of Ni in a-Si which takes place prior to the MILC growth.