本論文為應用於有機發光二極體顯示器外部補償系統之電流感測電路設計。有機發光二極體顯示器的畫素電路之薄膜電晶體會由於製程差異或在長時間的操作下元件老化衰退導致其臨界電壓與電子遷移率產生偏移現象。除此之外，有機發光二極體也會隨著使用時間產生衰退現象使得臨界電壓上升。上述因素將導致面板顯示品質降低，故本研究設計的電流感測電路將針對畫素電路內的驅動薄膜電晶體之臨界電壓與電子遷移率，以及有機發光二極體的衰退現象透過測量電流之方式進行感測。
此感測電路有200個通道，每個通道包含將畫素電流轉為電壓的電流積分器、電壓位準轉換器及取樣保持電路。研究中提出的電流積分器其放大器架構與頻率補償方式能夠克服面板負載影響，提高電流感測準確度及線性度。另外還加入了offset cancelling架構，解決每通道間各自放大器會有不同offset的問題，確保200個通道感測的一致性。
此感測電路所偵測之畫素電流範圍為-0.5μA~0.5μA，輸入電壓範圍為6V~9V，輸出電壓範圍為0.4V~1.4V，並操作在18V/1.8V工作電壓下。使用世界先進積體電路股份有限公司所提供的VIS 0.18μm 1P4M CMOS 高壓製程設計與下線。模擬結果其電流偵測解析度可達1nA。

In this thesis, the author designed a current sensing circuit for the external compensation of an active matrix organic light emitting diode (AMOLED) display. Due to process variation, the thin-film transistors (TFTs) in AMOLED display have different threshold voltage and electron mobility, also with long-term operation aging the device, the above characteristics may drift form one to another. Furthermore, threshold voltage of OLED rises with the degradation of the organic materials. consequently, these problems reduce the overall quality of the AMOLED display. Therefore, the current sensing circuit is designed to sense the electrical characteristics of these devices for latter external compensation.
The designed current sensing circuit has 200 channels, each channel includes a current integrator which transfer the sensed pixel current to a voltage output, a voltage level shifter and a sample and hold circuit. The proposed operational amplifier and its frequency compensation method used in the current integrator can cope with the effect of huge display panel loading, enhance the accuracy and linearity of the current sensing. Additionally, an offset cancelling technic implemented in the amplifiers could bring out uniform sensing qualities throughout 200 channels.
The input current range of the sensing circuit is -0.5μA~0.5μA, the input common mode voltage is 6V~9V, and the output voltage range is 0.4V~1.4V. The circuit operates under 18V/1.8V supply voltage, implemented using Vanguard International Semiconductor 0.18μm 1P6M CMOS high voltage process, and its current sensing accuracy can achieve 1nA.

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