Indirect-feedback Sigma-Delta CMOS image sensors with SAR-based startup

Author

Zhe Gao ; Liobe, John C. ; Balon, Mark ; Ignjatovic, Zeljko ; Fiscella, Mark ; Bocko, Mark F.

Author_Institution

Univ. of Rochester, Rochester, NY, USA

fYear

2015

fDate

21-21 April 2015

Firstpage

1

Lastpage

5

Abstract

A novel type of CMOS image sensor (CIS) leveraging two types of analog-to-digital converters (ADCs) is presented in this work. Contrary to conventional ΣΔ image sensors, which implement ΣΔ ADCs at the column or pixel array level, this work utilizes the pixel structure as part of the ΣΔ modulator to enhance the noise shaping capabilities of the readout scheme. The overall speed performance of this indirectfeedback (IF) ΣΔ image sensor is enhanced with the addition of a Successive Approximation Register (SAR) startup. The SAR startup has been successfully demonstrated on two prototype image sensors developed in a generic 0.35μm digital CMOS process. For the column-level, 320x180 pixel implementation, the SAR startup is included with minimal additional overhead, 1.8% of original ΣΔ column readout circuitry.

Keywords

CMOS image sensors; CMOS logic circuits; flip-flops; sigma-delta modulation; ΣΔ column readout circuitry; ΣΔ image sensors; ΣΔ modulator; SAR-based startup; analog-to-digital converters; digital CMOS process; indirect-feedback ΣΔ image sensor; noise shaping capability; pixel array level; readout scheme; sigma-delta CMOS image sensors; size 0.35 mum; successive approximation register startup; Arrays; CMOS image sensors; Noise; Photodiodes; Prototypes; Sigma-delta modulation; CMOS image sensor; Indirect-feedback ΣΔ image sensor; high dynamic range; time-domain simulator;

fLanguage

English

Publisher

ieee

Conference_Titel

Electrical, Electronic and Information Sciences (eStream), 2015 Open Conference of

Conference_Location

Vilnius

Type

conf

DOI

10.1109/eStream.2015.7119491

Filename

7119491