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Quarter Video Graphics Array Digital Pixel Image Sensing With a Linear and Wide- Dynamic-Range Response by Using Pixel-Wise 3-D Integration

2018; Institute of Electrical and Electronics Engineers; Volume: 66; Issue: 2 Linguagem: Inglês

10.1109/ted.2018.2885072

1557-9646

Masahide Goto, Yuki Honda, Toshihisa Watabe, Kei Hagiwara, Masakazu Nanba, Yoshinori Iguchi, Takuya Saraya, Masaharu Kobayashi, Eiji Higurashi, Hiroshi Toshiyoshi, Toshiro Hiramoto,

Image Processing Techniques and Applications

We have developed a quarter video graphics array (QVGA) digital pixel image sensor by using the 3-D integration technology. The pulse-frequency modulation (PFM) analog-to-digital converter (ADC) operates as a digital pixel, which overcomes the signal saturation due to the full well capacity of the photodiode (PD). We have also newly designed a PFM-ADC for pixels with a pinned PD and a floating diffusion to comply with the CMOS image sensor process used to attain high sensitivity and low noise. PDs, comparators, logic circuits, and counters are integrated into two silicon-on-insulator layers by pixel-wise 3-D integration with gold electrodes with a 5 μm diameter, thereby achieving a QVGA resolution for a 20-mm square chip in the 0.18and 0.2-μm process nodes. The developed sensor exhibits both the excellent linearity and a widedynamic range of more than 96 dB. Video images with a high bit depth of 16 bit are also obtained to demonstrate the superior image sensing, capable of capturing the real world at high fidelity.