温度系数可调的基准电压产生电路研究与设计

Study and Design of Reference Voltage Generator with Adjustable Temperature Coefficient

由于TFT～LCD显示屏的物理特性随温度而发生变化，驱动电路必须提供具有相同温度特性的驱动电压，以补偿显示屏的温度特性，进而提高显示画质。文章研究并设计了一种用于TFT—LCD彩屏手机驱动芯片的基准电压产生电路，其输出电压的绝对值与温度系数可编程调节，从而可实现与液晶显示屏的温度特性相匹配。介绍了该电路的各子模块电路，包括偏置电路、带隙基准电路和输出电压调节电路，详细分析了带隙基准电路所产生的基准电压的温度系数及其调节原理。用Hspice对采用0．25μmCMOS工艺设计的电路进行了仿真。仿真结果表明，基准电压的温度系数可从-1.24～1．13mV／℃变化，输出电压的绝对值可从1．8～2.1V调节，最大可提供负载电流40mA。

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 te/nperature 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.