Design On Driver Circuits for TFT-LCD Display

• Main Authors: Weh-Hsia Kung, 龔文俠
• Other Authors: Ming-Dou Ker
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/57131403361161220667

碩士 === 國立交通大學 === 電子工程系 === 90 === In this thesis, we focus on the driver circuits for TFT-LCD display. The driver circuits are divided into two parts, gate driver and data driver. Gate driver is composed of shift register, level shifter, and output buffer. Data driver is composed of shift register, level shifter, latch, digital to analog converter, and output buffer. Because the relationship of transparency versus voltage of liquid crystal is nonlinear, we design a digital to analog converter with gamma correction to compensate this effect. The circuit has been designed and fabricated in a 0.5µm CMOS process. In output buffer, we design two kinds of output buffer which can drive high loading. They are folded opamp and slew rate enhancement opamp. In addition, we design two circuits with charge recycling in order to reduce more power consumption. The circuit with half recycling can reduce about 1/2 dynamic power, and the circuits with triple charge recycling can reduce about 2/3 dynamic power. All of four circuits have been designed and fabricated in a 0.25µm CMOS process. Finally, we discuss the concept of using high performance low temperature poly silicon thin film transistor (LTPS-TFT) to directly fabricate the driver circuits on the display panel. The comparison on device characteristics between LTPS-TFT and high-voltage CMOS is investigated. In addition, we proposed two new circuits for pixels with digital memory. In the case of still images, the voltage of pixel electrode is refreshed by digital memory and it can shut down the peripheral driver circuits in the same time. So, it can save more power. The device dimensions and circuit operation of these two new circuits have been designed and verified by Smartspice simulation.