Image Lag Analysis and Photodiode Shape Optimization of 4T CMOS Pixels
نویسندگان
چکیده
A good charge transfer efficiency is very important for high-speed application CMOS image sensors. This paper presents a method to optimize the pinned-photodiode (PPD) shape, which is implemented in the 4T CMOS pixel for reducing the image lag of large area photodiode pixels. The new design allows combining a better light sensitivity with a good charge transfer. A CMOS image sensor test chip is designed for verifying the performance of the proposed pixel design. Comparing the performances of different PPD shape designs, the chip measurement results prove that the proposed “W” shape PPD achieves 1/27 image lag of traditional rectangular shaped PPDs. And with about 80% area of the rectangular shape, the light sensitivity of the proposed “W” shape PPD is comparable with the rectangular shape.
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