We have designed gate arrays using low-temperature poly-Si thin-film transistors and confirmed the correct operations. Various kinds of logic gates are beforehand prepared, contact holes are later bored, and mutual wiring is formed between the logic gates on demand. A half adder, two-bit decoder, and flip flop are composed as examples. The static behaviors are evaluated, and it is confirmed that the correct waveforms are output. The dynamic behaviors are also evaluated, and it is concluded that the dynamic behaviors of the gate array are less deteriorated than that of the independent circuit.

An integrated ambient light sensor (ALS) system in low-temperature polycrystalline silicon (LTPS) thin-film-transistor liquid-crystal-displays (TFT-LCDs) is proposed and prototyped in this study. It is designed as a 4-bit (16-step-grayscale) ALS and includes a noise subtraction circuit, a comparator as an analog-to-digital converter (ADC), 4-bit counters, and a parallel-to-serial converter. LTPS lateral p-i-n diodes with a long i-region are employed as photodetectors in the system. An LSI source driver is mounted on the LCD panel with a sensor control block which provides programmable clocks and reference voltages to the ALS circuit on the glass substrate for sensitivity tuning. The reliability tests were conducted for 300 hours with 30000 lux illumination at 70 °C and at -20 °C. The observed deviations of the ALS values for dark, 1000 lux, and 10000 lux were within ±1.

Ambient light sensors have been used to reduce power consumption of Active Matrix Liquid Crystal Displays (AMLCD) adjusting display brightness depending on ambient illumination. Discrete sensors have been commonly used for this purpose. They make module design complex. Therefore it has been required to integrate the sensors on the display panels for solving the issue. So far, many kinds of integrated sensors have been developed using Amorphous Silicon (a-Si) technology or Low Temperature Polycrystalline Silicon (LTPS) technology. These conventional integrated sensors have two problems. One is that LTPS sensors have less dynamic range due to the less photosensitivity of LTPS photodiodes. The other is that both the LTPS and a-Si sensors are susceptible to display driving noises. In this paper, we introduce a novel integrated sensor using both LTPS and a-Si technologies, which can solve these problems. It consists of vertical a-Si Schottky photodiodes and an LTPS differential converter circuit. The a-Si photodiodes have much higher photosensitivity than LTPS ones, and this contributes to wide dynamic range and high accuracy. The LTPS differential converter circuit converts photocurrent of the photodiodes to a robust digital signal. In addition it has a function of canceling the influences of the display driving noises. With the circuit, the sensor can stably and accurately work even under the noises. The performance of the sensor introduced in this paper was measured to verify the advantages of the novel design. The measurement result showed that it worked in a wide ambient illuminance range of 5-55,000 lux with small errors of below 5%. It was also verified that it stably and accurately worked even under the display driving noise. Thus the sensor introduced in this paper achieved the wide dynamic range and noise robustness.

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.

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."