Study and Design of Reference Voltage Generator with Adjustable Temperature Coefficient
Tingcun Wei · Chinese Journal of Liquid Crystals and Displays · 2006
Because the physical properties of TFT-LCD panel changes with the temperature, TFT-LCD driver circuits must supply the driving voltages with the same temperature properties as TFT-LCD panel, so that the temperature properties of TFT-LCD panel can be compensated and the image display quality can be improved. In this paper, the reference voltage generator used for TFT-LCD driver IC of mobile phone is studied and designed, in which the absolute value and temperature coefficient of output voltage can be adjusted by programming, and the output voltage can be matched with the temperature properties of TFT-LCD panel very well. Firstly the sub-blocks including bias circuit, bandgap reference , and voltage regulator circuit are introduced, and then the temperature coefficient adjustment of voltage generated by bandgap reference is analyzed. Finally, the Hspice simulation results of the circuits designed using 0.25 μm COMS process are given. It is shown that the temperature coefficient and the absolute value of output voltage can be adjusted from -1.24 ~ 1.13 mV/℃ and 1.8 ~ 2.1 V, respectively, and the load capability of output voltage is larger than 40 mA.