Abstract
In the thesis, an 8-bit compact digital to analog converter for TFT-LCD source driver ICs with scanning decoders is purposed. Currently, the requirement of LCD market is toward to large size, high resolution development. Especially the digital to analog converter (DAC) of column driver ICs, how to arrive requirement of large size and high resolution but will achieve purposed of reducing area are always the important specifications. DAC with scanning decoders costs less area than conventional DAC. The conventional DAC for LCD column driver ICs makes use of a resistor string dividing voltage, after that, going through each channel of decoder to select the voltage of corresponding data to show the color. DAC with scanning decoders makes use of the two stage switches to select the voltage sequentially. When the voltage corresponding to the data being selected, the switches will stop sequentially turn on switches and the buffer output will arrive the voltage corresponding to the data, after that, giving the liquid crystal different twist angle to show the color on display. As column driver ICs in need of many channels as concerned, taking advantage of second stage switches instead of decoders especially for the high resolution column driver will cost many areas down. This research prototype was realized in TSMC 0.35μm 2P4M technology. This chip is 8 bit DAC for 8 channels with the worst DNL/INL of 0.32/0.37 LSB. The settling time of the output buffer spends 4.5us. The area of each channel is 0.014mm2, which occupies only 27 % of the conventional 8-bit RDAC area.