Development of a CMOS low-noise analog front-end ASIC for X-ray imaging applications

High density compound materials (CdTe, GaAs, HgI/sub 2/) are currently evaluated as direct photon conversion sensors for applications in X-ray imaging. A new front-end stage has been designed with the aim to be implemented as readout chain in a luggage inspection system based on a linear array of CdTe sensors. Both types of electron or hole collecting CdTe sensors will be evaluated. Each detecting element is characterized by leakage current smaller than 5nA/mm/sup 2/ at working point and capacitance in the range of 0.5pF. A low noise front-end chain has been developed based on the voltage mode architecture. The operation of the front-end stage is optimized for a 2pF capacitance, system input capacitance, and for energy range of 20-220keV. A prototype ASIC has been fabricated in a commercial 0.6um CMOS process.