A Compensation System using Analog Voltage Adder with Continuous Output for AMOLED Display Drivers

Hezi Qiu, Jian Liang, Wenlong Bai, Hing-Mo Lam, Junjun An, Congwei Liao, Min Zhang, Hailong Jiao, Shengdong Zhang

Abstract: An on-chip compensation system which is composed of an analog voltage adder and an 8-bit R-C digital-to-analog converter (DAC) is proposed for active matrix organic light-emitting diode (AMOLED) display drivers. The proposed analog voltage adder uses two groups of rail-to-rail input MOSFETs, which can work alternately, thereby extending the effective driving time (EDT) to 100%. The 8-bit R-C DAC is composed of a 5-bit R-DAC and a 3-bit C-DAC. The 3-bit C-DAC shares the capacitors with the analog voltage adder, reducing the layout area by 65% compared to the conventional method. This work is implemented in an industrial 0.18-μm CMOS technology. The measurement results show that the maximum INL of the system is 0.254 LSB, while the maximum DNL is 0.506 LSB. The layout area is only 9180 μm 2 per channel.