Digital linearity correction of a wide dynamic range current-mode image sensor

Khamsehashari, Elham; Audet, Yves; Fayomi, Christian

doi:10.1109/newcas.2010.5603722

Cited by 2 publications

(2 citation statements)

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“…The non-linearity comes mainly from the hole mobility degradation of transistor M 2 as a function of V GS and the ''on'' resistance of the select transistor M 3 . A solution for the non-linearity imposed by the transistor M 3 'on' resistance which results in an increasing drain-source voltage drop as the output current increases, has been proposed in [15] using a digital correction method. The image lag effect shown in Figure 3, due to the dependence of the reset photosite voltage on the light intensity, affects the image quality.…”

Section: System Architecture and Operationmentioning

confidence: 99%

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Response Mode Detection of a Linear-Logarithmic Image Sensor Using a Current-Mode Readout Circuit

Khamsehashari

Audet

2013

CSSP

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A current-mode image sensor architecture using a linear-logarithmic pixel in order to improve the dynamic range is presented. The pixel cell is based on a 3T active pixel structure with a PMOS readout transistor in the linear region of operation and a PMOS reset transistor that allows for a linear-logarithmic response. An intrascene dynamic range of 90dB is obtained with a pixel fill factor of 37%. The readout circuit is composed of a first-generation current conveyor, a current memory employed as a delta reset sampling unit, a differential amplifier used as an integrator and a dynamic comparator. The pixel response operating mode is determined in the column readout. A signal is sent to the digital processing unit as an indicator to determine the pixel response operating mode in order to allow the proper analog to digital conversion. The image lag effect observed in the pixel output current is removed by the delta reset sampling circuit. Experimental results, obtained from a test structure, are presented. The circuit was fabricated in a CMOS 0.35um process from Austria Microsystems.

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Section: System Architecture and Operationmentioning

confidence: 99%

“…Part of this work has been reported in the IEEE NEWCAS conference proceedings [15][16], new key experimental results are presented to complete this work. This paper is organized as follow.…”

Section: Introductionmentioning

confidence: 99%