主動式有機發光二極體(AMOLED)被視為次世代的顯示技術，由於其廣視角、快的反應速度、高對比、高色彩飽和度、和自發光性等特性，已經可以與發展成熟的TFT-LCD相比擬了，使其近年來受到市場上相當的矚目。由於OLED是一電流驅動元件而其電流是由電源線以及TFT背板所產生的，因此在經過長時間的操作下，畫面是否能維持正常全都取決於驅動電流的精度，這也意謂著背板技術的重要性。在許多的背板技術中，低溫多晶矽（LTPS）所製成的薄膜電晶體便具有高載子飄移率，使得畫素電路尺寸微縮，進而達到較大的開口率，提升顯示器品質。然而，低溫多晶矽薄膜電晶體製程過程中，在準分子雷射退火時會造成的電性差異，導致整體顯示器的不均勻性。因此，金屬氧化物薄膜電晶體(a-IGZO TFT)開始被重視，許多研究指出氧化銦鎵鋅（IGZO）有不錯的電特性、大面積製程上較為均勻以及製程成本較低的優點，使其在顯示器技術上有相當的優勢。然而，在長時間操作下其電特性會偏移，造成電流分布不均勻進而降低顯示器品質。因此，近幾年出現了有關於畫素電路補償之研究。然而，以近三年畫素電路補償設計的文獻得知[9]-[16]，TFT數量與電容數量明顯偏多，使開口率下降，因此第一個畫素電路設計是以精簡的TFT數量與電容數量來達到與文獻中所提之補償電路具有相同補償能力，另外，模擬結果顯示，在薄膜電晶體的臨界電壓飄移正負2Ｖ時，此電路的平均電流錯誤率僅有1.475%。
從目前近三年文獻可以得知[9]-[16]，在OLED老化抑制與mobility變化的補償無法有效將兩者整合在同一電路內，因此，第二個電路提出了一種新的整合方式，其具備上下發光結構的特點。並且透過使用兩種不同的信號模式，即A和B模式，在A與B模式中皆補償driving TFT的閥值電壓，VDD電源線造成的電壓下降和OLED的閥值電壓，而A模式和B模式的區別在於A模式是透過輸入反向偏壓來抑制OLED老化，而B模式主要是用於補償driving TFT mobility變化，從模擬結果顯示，在A模式中，電晶體的臨界電壓飄移正負±1.5V時，其電流錯誤率小於1.5%，而VDD的下降1V與OLED閥值增加1V時，相對最大電流錯誤率分別為4.66%和4.53%；在B模式中，電晶體的臨界電壓飄移正負±1.5V時的相對電流錯誤率小於5.5%，而VDD下降1V與OLED閥值增加1V時的相對最大電流錯誤率皆小於0.2%，另外在driving TFT mobility變化±50%所造成的最大電流錯誤率小於10%。

AMOLED is considered a next-generation display technology because its wide viewing angle, short response time, high contrast ratio, high color saturation, and self-emission make it comparable to mature TFT-liquid crystal displays and popular in the market. However, an OLED is a current driving device, with the driving current generated by a power line and a TFT backplane; therefore, whether a display can function properly for a prolonged period depends on the precision of the current. This highlights the importance of TFT backplane technologies. Among TFT backplane technologies, TFTs developed with low-temperature polycrystalline silicon possess a high carrier mobility, which slightly reduces the size of the pixel circuit and increases aperture ratio as a result, thereby improving display quality. However, the production of such TFTs involves an excimer-laser annealing process that leads to an electrical property contrast and, in turn, non-uniformity across the display. Emphasis has therefore been shifted to amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs. Many researchers have argued that IGZO—which has robust electrical properties, allows for uniform large-area processing, and is cheaper to produce—is a widely favored material for displays. However, once the display is used for a long period of time, the electrical properties of IGZO begin to shift, rendering the distribution of currents non-uniform and affecting the display’s quality. Studies on pixel circuit compensation have been conducted to address this limitation, although the related studies in the past three years [9]-[16] have suggested that TFTs and capacitors tend to be too numerous, resulting in decreased aperture ratios. This argument led one function of a proposed 3T2C pixel circuit being designed, which involved using a reduced number of TFTs and capacitors to perform compensations comparable to those performed by the compensatory circuits described in the literature. Furthermore, simulation results suggested that when the VTH shifted to ± 2 V, the proposed pixel circuit achieved an average current error rate of only 1.475%.
Related studies in the past three years [9]-[16] have indicated the OLED aging suppression and mobility variation compensation cannot effectively integrate both into the same circuit. Thus, the second 3T1C pixel circuit is presented to satisfy this requirement. The proposed 3T1C pixel circuit has the characteristics of upper and lower luminescence structures. Additionally, integration is achieved by using two different signal modes, namely modes A and B. Modes A and B compensate for threshold voltage (VTH) variations of TFTs, VDD IR drops, and VTH_OLED variations of OLEDs. The difference between mode A and B is that OLED aging is suppressed through reverse bias in mode A, whereas the mobility shift of the DTFT is compensated for in mode B. The simulation results shows that in mode A, the relative OLED current error rates with threshold voltage shifts ±1.5V are less than 1.5%. The relative maximum current error rate of VDD drops 1V and the 1V shift of threshold voltage of the OLED is 4.66% and 4.53%, respectively. In mode B, the relative current error rates with ±1.5 V variations in threshold voltage of DTFT are less than 5.5%. The relative maximum current error rate of VDD drops 1V and the threshold voltage of OLED shifts 1 V are less than 0.2%. The maximum current error rate caused by the ±50% error rate of DTFT mobility is less than 10%.

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