開發一主動矩陣有機發光二極體顯示器之電流讀取電路

Abstract

本論文針對電壓驅動所導致之主動矩陣有機發光二極體顯示器的有機發光二極體元件劣化，製程漂移等因素，在顯示器面板外部設計一款互補式金屬氧化半導體電流讀取電路，讀取顯示器面板中以六個薄膜氧化電晶體和一個電容組成的畫素電路之電流大小。首先設計一單位增益緩衝器對面板的電流感測線做預充電，其目的是加速面板畫素電路電流進入外部電路。然後設計一定電壓電路，對畫素電路之有機發光二極體的陽極做定電壓，使有機發光二極體在外部電路做電流感測時不導通電流。最後提出使用開關電容積分器對畫素電路的電流做積分操作，以達到電流輸入、電壓輸出的效果。輸入的電流越大，積分器輸出電壓的斜率越大，從而完成電流感測的功能。感測電流的大小範圍在50nA至300nA，感測時間小於7us。

This thesis presents a CMOS current readout circuit in external active matrix organic light emitting diodes (AMOLED) for sensing thin-film transistor (TFT) current of AMOLED 6T1C pixel circuit, due to TFT current is extremely sensitive to the process drift by voltage-mode driving and OLED degradation. First of all, a Unity-gain buffer is designed to pre-charge the AMOLED current sensing line, for enhancing the TFT current speed flowing into the current readout circuit. Second, a voltage-fixed circuit is designed to fix the OLED anode voltage, make the OLED have no current flowing when the TFT current is being sensed. At last, a Switched-Capacitor Integrator is designed for integrating the TFT current, in order to make the circuit have current input voltage output. The greater input current are, the greater slope value of the integrator output, thus, the sensing current function was completed. The sensing current value between 50nA to 300nA, sensing time less than 7us.