A wide dynamic range CMOS digital pixel sensor

Author

Trepanier, J.-L. ; Sawan, M. ; Audet, Y. ; Coulombe, J.

Author_Institution

Dept. of Electr. Eng., Ecole Polytech. de Montreal, Que., Canada

Volume

2

fYear

2002

fDate

4-7 Aug. 2002

Abstract

A CMOS image sensor with pixel level analog to digital conversion is presented. Each 13.8μm × 13.8μm pixel area contains a photodiode and a dynamic comparator using the maximum voltage swing available (0V-1.8V). The comparator does not need any bias current and is insensitive to fabrication process variations. Also a digital to analog converter (DAC) is used to deliver a voltage reference in order to compare it with the pixel voltage for the analog to digital conversion. This DAC provides the possibility to convert the pixel voltage linearly or to compress it logarithmically. The circuit allows image captures at multiple exposure times, and the resulting values are delivered in floating digital format, offering the possibility to expand the intrascene dynamic range to more than 84 dB. The circuit was implemented in a CMOS 0.18μm process and has been submitted for fabrication.

Keywords

CMOS image sensors; analogue-digital conversion; comparators (circuits); photodiodes; 0 to 1.8 V; 0.18 micron; 13.8 micron; CMOS digital pixel sensor; bias current; dynamic comparator; floating digital format; image captures; intrascene dynamic range; multiple exposure times; photodiode; pixel level analog to digital conversion; voltage reference; Analog-digital conversion; CMOS image sensors; Circuits; Digital-analog conversion; Dynamic range; Fabrication; Image converters; Photodiodes; Pixel; Voltage;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems, 2002. MWSCAS-2002. The 2002 45th Midwest Symposium on

Print_ISBN

0-7803-7523-8

Type

conf

DOI

10.1109/MWSCAS.2002.1186892

Filename

1186892