臺灣博碩士論文加值系統

近年來，應用影像感測器做為資料獲取方式逐漸增加，例如在自動駕駛中可以透過影像感測器來判定周遭環境，以提供自動駕駛的功能及提升行車安全。或是在醫療領域使用大面積的感測器作為X光感測的接收器，目的在提升可拍攝範圍及影像感測的準確度。因此，對於影像感測器的解析度以及辨識正確度的要求也隨之提升。主動式畫素感測器（APS）中經常使用的TFT元件容易受到製程和溫度等因素的影響，這會改變其特性並進而影響感測的精準度，且元件的臨界電壓（Vth）漂移是其中最主要的影響因素。
相關性二次取樣（CDS）是一種經常被用於消除元件特性漂移的技術。傳統上，這種技術通常透過運算放大器與切換電容的組合來實現。不過，運算放大器和類比數位轉換器（ADC）都有其可正常操作的電壓範圍。如果輸入信號的電壓值因為元件特性漂移而超出這個範圍，信號在傳輸過程中可能會產生遺失，導致無法精確讀取感測信號。
論文提出了一種新型CDS電路，該電路由TFT與電容組成，可以與感測陣列面板整合。其優勢在於，信號在進入IC之前便已消除了Vth的變異，同時調整了輸出電壓的動態範圍，以匹配類比數位轉換器的可操作電壓範圍。在論文中首先使用HSPICE進行電路模擬以確認電路的可行性，並且透過實際產出電路，分別進行了離散量測與實際應用於感測陣列面板中的量測，最後從量測的實驗中得出此電路可以有效補償薄膜電晶體臨界電壓的飄移，進而使感測影像均勻度得到顯著提升。

In recent years, the use of image sensors for data acquisition has been on the rise in various scenarios. For instance, in autonomous driving, image sensors can assess the surrounding environment to enable autonomous driving functions and improve road safety. In the medical field, large-area sensors are used as X-ray detectors to increase the range of imaging and improve imaging accuracy. Consequently, the demand for higher resolution and greater accuracy in image sensors has also increased.
The thin-film transistor (TFT) elements commonly used in active pixel sensors (APS) are susceptible to influences such as manufacturing processes and temperature, which can alter their characteristics and impact sensing accuracy. Among the factors affecting the precision of sensing, the threshold voltage (Vth) drift of the devices is a major concern.
Correlated double sampling (CDS) is a commonly used technique to eliminate device characteristic drift. Traditionally, this technique is typically implemented using a combination of operational amplifiers and switched capacitors. However, operational amplifiers and analog-to-digital converters (ADCs) have their own normal operating voltage ranges. If the voltage values of the input signals exceed this range due to device characteristic drift, signal loss may occur during transmission, making it impossible to accurately read the sensing signals.
Hence, we propose a novel CDS circuit consisting of TFTs and capacitors, which can be integrated with sensing array panels. The advantage of this circuit is that it eliminates Vth variation before the signal enters the IC and adjusts the dynamic range of the output voltage to match the operable voltage range of the ADC. In the paper, the circuit feasibility is initially confirmed through HSPICE simulation, followed by discrete measurements and actual application of the circuit in sensing array panels. The results from these measurements demonstrate that the circuit effectively compensates for thin-film transistor threshold voltage drift, significantly improving the uniformity of the sensed images.

Contents
摘要i
Abstractii
Contentsiv
Figure Captionvi
Table Captionviii
Chapter. 1Introduction1
1.1Background1
1.2Motivation4
1.3Thesis Organization6
Chapter. 2On-Panel CDS Circuit8
2.1Overview of the Proposed Circuit8
2.1.1Structure of the Proposed CDS Circuit8
2.1.2Operation of the Proposed Circuit10
2.2Simulation Result12
2.2.1Simulation Setting12
2.2.2Simulation Results13
2.3Summary14
Chapter. 3Discrete CDS Circuit Implementation15
3.1Verification Method15
3.2Circuit Fabrication and Experiment System Setup17
3.3Measurement Results18
3.4Summary19
Chapter. 4Panel CDS Circuit Implementation20
4.1Threshold Voltage Tuning Method20
4.2Measurement Results21
4.2.1Output Image without CDS21
4.2.2Output Image with IC CDS22
4.2.3Output Image with IC and Panel CDS22
4.3Comparison and Discussion23
4.4Summary25
Chapter. 5Conclusion26

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