Design and Evaluation of a CMOS-Photosensor with In-Pixel Sigma-Delta Modulator for X-ray Computed Tomography

Author

Bäumer, Christian ; Eick, Stefan ; Steadman, Roger ; Vogtmeier, Gereon ; Gnade, Michael ; Kemna, Armin ; Weiler, Dirk

Author_Institution

Philips Res. Labs. Eur., Aachen

fYear

2006

fDate

Sept. 2006

Firstpage

432

Lastpage

435

Abstract

A multichannel SigmaDelta-type analog-to-digital converter has been designed for data readout in CT scanners. A test-structure with a 4 times 4 photodetector array has been fabricated in a 0.8 mum CMOS process. Aiming at an integrated solution towards a ´digital pixel´, each sensor element is formed by a photodiode and a third-order SigmaDelta-modulator. The switched-capacitor circuitry has been realized as a fully differential-path design. Test measurements have been carried out and analyzed in terms of dynamic range and noise. Simulations on layout level have been performed. A digital post-processing scheme has been devised for decimation and low-pass filtering of the modulator outputs

Keywords

CMOS image sensors; computerised tomography; photodetectors; photodiodes; sigma-delta modulation; switched capacitor networks; 0.8 micron; CMOS process; CMOS-photosensor design; CT scanners; SigmaDelta-type analog-to-digital converter; X-ray computed tomography; data readout; digital pixel; low-pass filtering; photodetector array; photodiode; sigma-delta modulator; switched-capacitor circuitry; Analog-digital conversion; CMOS process; Circuit testing; Computed tomography; Delta-sigma modulation; Noise measurement; Photodetectors; Photodiodes; Switched capacitor circuits; X-ray imaging;

fLanguage

English

Publisher

ieee

Conference_Titel

Solid-State Circuits Conference, 2006. ESSCIRC 2006. Proceedings of the 32nd European

Conference_Location

Montreux

ISSN

1930-8833

Print_ISBN

1-4244-0303-0

Type

conf

DOI

10.1109/ESSCIR.2006.307473

Filename

4099796