A CMOS image sensor using floating capacitor load readout operation

S. Wakashima, Y. Goda, T. L. Li, R. Kuroda, S. Sugawa

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

In this paper, a CMOS image sensor using floating capacitor load readout operation has been discussed. The floating capacitor load readout operation is used during pixel signals readout. And this operation has two features: 1. in-pixel driver transistor drives load capacitor without current sources, 2. parasitic capacitor of pixel output vertical signal line is used as a sample/hold capacitor. This operation produces three advantages: a smaller chip size, a lower power consumption, and a lower output noise than conventional CMOS image sensors. The prototype CMOS image sensor has been produced using 0.18 μm 1-Poly 3-Metal CMOS process technology with pinned photodiodes. The chip size is 2.5 mmH × 2.5 mmV, the pixel size is 4.5 μmH × 4.5 μmV, and the number of pixels is 400 H x 300 V. This image sensor consists of only a pixel array, vertical and horizontal shift registers, column source followers of which height is as low as that of some pixels and output buffers. The size of peripheral circuit is reduced by 90.2 % of a conventional CMOS image sensor. The power consumption in pixel array is reduced by 96.9 %. Even if the power consumption of column source follower is included, it reduced by 39.0 %. With an introduction of buried channel transistors as in-pixel driver transistors, the dark random noise of pixels of the floating capacitor load readout operation CMOS image sensor is 168 μV rms. The noise of conventional image sensor is 466 μV rms; therefore, reduction of 63.8 % of noise was achieved.

Original languageEnglish
Title of host publicationProceedings of SPIE-IS and T Electronic Imaging - Sensors, Cameras, and Systems for Industrial and Scientific Applications XIV
DOIs
Publication statusPublished - 2013 Apr 10
EventSensors, Cameras, and Systems for Industrial and Scientific Applications XIV - Burlingame, CA, United States
Duration: 2013 Feb 62013 Feb 7

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume8659
ISSN (Print)0277-786X

Other

OtherSensors, Cameras, and Systems for Industrial and Scientific Applications XIV
CountryUnited States
CityBurlingame, CA
Period13/2/613/2/7

Keywords

  • CMOS image sensor
  • RTN
  • floating capacitor
  • low noise
  • low power consumption
  • random noise
  • small chip size

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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  • Cite this

    Wakashima, S., Goda, Y., Li, T. L., Kuroda, R., & Sugawa, S. (2013). A CMOS image sensor using floating capacitor load readout operation. In Proceedings of SPIE-IS and T Electronic Imaging - Sensors, Cameras, and Systems for Industrial and Scientific Applications XIV [86590I] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 8659). https://doi.org/10.1117/12.2004892