Title :
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
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;
Conference_Titel :
Solid-State Circuits Conference, 2006. ESSCIRC 2006. Proceedings of the 32nd European
Conference_Location :
Montreux
Print_ISBN :
1-4244-0303-0
DOI :
10.1109/ESSCIR.2006.307473
