Analysis of pixel gain and linearity of CMOS image sensor using floating capacitor load readout operation

S. Wakashima, F. Kusuhara, R. Kuroda, S. Sugawa

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

5 Citations (Scopus)

Abstract

In this paper, we demonstrate that the floating capacitor load readout operation has higher readout gain and wider linearity range than conventional pixel readout operation, and report the reason. The pixel signal readout gain is determined by the transconductance, the backgate transconductance and the output resistance of the in-pixel driver transistor and the load resistance. In floating capacitor load readout operation, since there is no current source and the load is the sample/hold capacitor only, the load resistance approaches infinity. Therefore readout gain is larger than that of conventional readout operation. And in floating capacitor load readout operation, there is no current source and the amount of voltage drop is smaller than that of conventional readout operation. Therefore the linearity range is enlarged for both high and low voltage limits in comparison to the conventional readout operation. The effect of linearity range enlargement becomes more advantageous when decreasing the power supply voltage for the lower power consumption. To confirm these effects, we fabricated a prototype chip using 0.18um 1-Poly 3-Metal CMOS process technology with pinned PD. As a result, we confirmed that floating capacitor load readout operation increases both readout gain and linearity range.

Original languageEnglish
Title of host publicationProceedings of SPIE-IS and T Electronic Imaging - Image Sensors and Imaging Systems 2015
EditorsRalf Widenhorn, Antoine Dupret
PublisherSPIE
ISBN (Electronic)9781628414936
DOIs
Publication statusPublished - 2015 Jan 1
EventImage Sensors and Imaging Systems 2015 - San Francisco, United States
Duration: 2015 Feb 92015 Feb 10

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9403
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Other

OtherImage Sensors and Imaging Systems 2015
Country/TerritoryUnited States
CitySan Francisco
Period15/2/915/2/10

Keywords

  • Floating Capacitor Load Readout Operation
  • High Readout Gain
  • Low Power Consumption
  • Wide Dynamic Range

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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