A 0.014mm2 9b switched-current DAC for AMOLED mobile display drivers

Active-Matrix Organic LED (AMOLED) technology has attracted a considerable amount of attention as a very desirable display due to superior characteristics such as its wide viewing angle, fast response, thinness, and low power consumption. Among various driving techniques for AMOLED displays, the current-driving scheme deals well with the issues of spatial and temporal variation of the TFT as well as IR drops in the pixel circuits [1]. Several previous works have successfully demonstrated this [2–3]. Figure 17.9.1 shows a block diagram of an AMOLED display system adopting a current-driving scheme. The digital-to-analog converter (DAC) plays a key role in the column driver by reconstructing the analog signal for pixel-driving from digital data. Considering that the number of columns of pixels continues to increase, even in mobile-oriented displays, the chip area occupied by the DAC should be greatly reduced. Furthermore, as widescreen displays such as WXGA are coming into wider use, it is necessary for column drivers for these displays to have a narrow channel pitch.