應用於XGA高解析度影像擷取之新式低電壓對數-線性型CMOS影像感測器

A New Low-Voltage Log-Lin Response CMOS Image Sensor for XGA

吳建瑩(Chien-Ying Wu)

指導教授 ： 吳紹懋

元智大學/工程學院/電機工程學系/碩士(2005年)

摘要

在本論文中設計、分析了一個應用於XGA高解析度影像擷取之新式低電壓對數-線性型CMOS影像感測器、並以台積電0.35μm 2P4M CMOS 製程實現。此新型影像感測器之感應像素，在低照度時具有對數性響應特性，在高照度時則具有如同傳統線性型感測器之高輸出擺幅電壓。與傳統型的感測器相比較，此設計的感測器可以改良動態範圍與輸出擺幅電壓的限制。除此，此新型之感測器具有減少內在像素固定雜訊的機制。在整個感測器的設計上，考量了在XGA解析度設計時的非理想效應。
在理論的推導及模擬中，可證明此新型感測器具有對數-線性型響應、高動態範圍、高輸出擺幅及減少內在像素固定雜訊的特性，此外本論文並針對XGA解析度的規格來做設計模擬及考量，但礙於晶片面積的限制，而分別以80x60及128x128的解析度來實現。

關鍵字

高解析度 ； 解析度 ； 對數性 ； 線性型 ； 感測器

並列摘要

In this thesis, a low-voltage log-lin response CMOS image sensor for XGA is analyzed, designed and implemented in TSMC 0.35μm standard process. The new pixel cell has logarithmic response at low illumination and high output swing as well as linear response at high illumination intensity. It can use the logarithmic response to enhance the minimum detectable photocurrent at low illumination; at high illumination it can detect the maximum photocurrent by adjusting the integration time. In contrast to the conventional pixels, the dynamic range limit and output swing can be improved. Furthermore, this proposed pixel has in-pixel CDS operation to reduce the fixed pattern noise and high sensitivity at low illumination. In the whole image sensor, non-ideality effects have also been considered for XGA application.

By theoretical analysis and simulation, we demonstrate that this new CIS pixel owns the logarithmic and the linear characteristics with high dynamic range, high output swing and in-pixel fixed-pattern noise reduction. In particular, it is operating from a single 1.8V supply while realized in a TSMC 0.35μm CMOS 2P4M standard process. For prototyping purpose, an 80x60 and a 128x128 photodiode arrays are implemented. The simulation results are demonstrated for XGA resolution.

並列關鍵字

CMOS ； CDS ； Dynamic Range ； XGA

參考文獻

[1] Liang-Wei Lai, Cheng-Hsiao Lai and Ya-Chin King, “A Novel Logarithmic Response CMOS Image Sensor With High Output Voltage Swing and In-Pixel Fixed-pattern noise Reduction,” IEEE SENSORS JOURNAL, vol. 4, No. 1, February. 2004.

[2] Hsien-Chun Chang, Ya-Chin King, Tunable Injection Current Compensation Architecture for High Fill-Factor Self-Buffered Active Pixel Sensor, Master’s Thesis, National Tsing Hua University, ROC, June 2002.

[3] H.S. Wong, “Technology and Device Scaling Considerations for CMOS Imagers,” IEEE Transaction on Electron Devices, vol.45, no. 12, pp.2131-.2142,.Dec.1996.

[5] V. Gruev, et al., “Linear current-mode imager with low fix-pattern noise,” IEEE ISCAS’04, May 2004.

[7] Eric C. Fox, et al., “Wide-Dynamic-Range Pixel with Combined Linear and Logarithmic Response and Increased Signal Swing,” Proceedings SPIE, vol. 3965, Jan 2000.