Simple pixel circuits for high resolution and high image quality organic light emitting diode-on-silicon microdisplays with wide data voltage range

Abstract

Two simple pixel circuits are proposed for high resolution and high image quality organic light-emitting diode-on-silicon microdisplays. The proposed pixel circuits achieve high resolution due to simple pixel structure comprising three n-type MOSFETs and one storage capacitor, which are integrated into a unit subpixel area of 3 × 9 µm2 using a 90 nm CMOS process. The proposed pixel circuits improve image quality by compensating for the threshold voltage variation of the driving transistors and extending the data voltage range. To verify the performance of the proposed pixel circuits, the emission currents of 24 pixel circuits are measured. The measured emission current deviation error of the proposed pixel circuits A and B ranges from −2.59% to +2.78%, and from −1.86% to +1.84%, respectively, which are improved from the emission current deviation error of the conventional current-source type pixel circuit when the threshold voltage variation is not compensated for, which ranges from −14.87% to +14.67%. In addition, the data voltage ranges of the proposed pixel circuits A and B are 1.193 V and 1.792 V, respectively, which are 2.38 and 3.57 times wider than the data voltage range of the conventional current-source type pixel circuit of 0.501 V.