Design and Optimization of a Twisted Photodiode Pixel Structure for All-Directional Phase-Detection Autofocus CMOS Image Sensors

Sensors 2026 Open access

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Authors: Daiki Shirahige, Koichi Fukuda, Hajime Ikeda, Yusuke Onuki, Ginjiro Toyoguchi, Kohei Okamoto, Shunichi Wakashima, Hiroshi Sekine, Shuhei Hayashi, Ryo Yoshida, Junji Iwata, Yasushi Matsuno
+3 more Katsuhito Sakurai, Hiroshi Yuzurihara, Takeshi Ichikawa
DOI: 10.3390/s26061758
Cited by: 0
References: 11

Abstract

To achieve an all-directional and high-speed, high-accuracy autofocus (AF) function, we propose a CMOS image sensor with a Twisted Photodiode (PD) structure. The developed 3D-stacked back-side illuminated (BSI) sensor employs the Twisted PD, which enables equivalent angular response characteristics in both the horizontal and vertical directions for the two PDs integrated within a single pixel, thereby realizing AF detection for all pixels and all directions. This paper describes the Twisted PD structure that enables all-directional AF and presents an analysis of charge transfer behavior in this unique 3D configuration. In this paper, "all-directional" refers to robustness with respect to subject direction.

Fields of Study & Subjects

CCD and CMOS Imaging Sensors Advanced Optical Sensing Technologies Image Processing Techniques and Applications

Publication details

Journal / source
Sensors
Volume
26
Issue
6
Pages
1758–1758
Publication date
10 March 2026
Language
EN