Counting and integrating microelectronics development for direct conversion x-ray imaging [Elektronische Ressource] / von Edgar Kraft. Universität Bonn, Physikalisches Institut

..UNIVERSITAT BONNPhysikalisches InstitutCounting and Integrating Microelectronics Development forDirect Conversion X-ray ImagingvonEdgar KraftA novel signal processing concept for X-ray imaging with directly con-verting pixelated semiconductor sensors is presented. The novelty of thisapproach compared to existing concepts is the combination of chargeintegration and photon counting in every single pixel. Simultaneous ope-ration of both signal processing chains extends the dynamic range beyondthe limits of the individual schemes and allows determination of the meanphoton energy. Medical applications such as X-ray computed tomographycan benefit from this additional spectral information through improvedcontrast and the ability to determine the hardening of the tube spec-trum due to attenuation by the scanned object. A prototype chip in0.35-micrometer technology has been successfully tested. The pixel elec-tronics are designed using a low-swing differential current mode logic.Key element is a configurable feedback circuit for the charge sensitiveamplifier which provides continuous reset, leakage current compensationand replicates the input signal for the integrator. The electronic characte-rization of a second generation prototype chip is described and a detaileddiscussion of the circuit design is given.