Design of a Peripheral-Circuit-Compensation Adjustable-Gamma-Voltage Driving Chip for OLED-on-Silicon Microdisplay

In this paper, a chip of driving integrated circuit with a resolution of 640×480 and a refresh rate of 60 Hz for microdisplay is proposed. The pixel circuit can detect and feed back the potential of OLED anode to determine the compensation data signal, thereby solving the problem of threshold voltage drift caused by OLED aging. The gamma voltage is adjustable to accommodate the brightness and contrast requirements of the microdisplay in different environments, since the gamma voltage is generated by additional DAC. Based on 0.18 μm process, the simulation results show that the proposed driving chip can achieve a grayscale of 256 levels and a refresh rate of 60Hz at 25MHz clock frequency. The output OLED pixel current range is 27 pA ~ 48.3 nA, the microdisplay brightness can reach 7400 cd/m
²
, and the contrast ratio can reach 1400:1.