Area-efficient Ramp Signal-based Column Driving Technique for AMOLED Panels

This work proposes a ramp signal-based column driving technique to maximize the area efficiency of the column driver integrated circuit (IC) for high-resolution active-matrix organic light emitting diodes (AMOLED) panels. The proposed column driving technique replaces the 2(n) reference voltages coming from the conventional n-bit resistor digital-to-analog converters (RDAC) with a single ramp signal, thereby reducing the area of the column driver IC by 44.3%. A weighted two-step interpolation structure, composed of the first-stage 6-bit ramp signal and the second-stage 2-bit amplifier DAC, reduces the required operation speed of the ramp signal under a limited 1-horizontal (1-H) time, while processing 8-bit image signals. The performance of the proposed column driving technique is verified with a 96-channel prototype IC fabricated in a 0.18 mu m CMOS process. The deviation of voltage output (DVO) of the prototype IC are within +/- 6 mV, and the unit channel area is 4200 mu m(2).