A CMOS detector readout front-end for X-ray digital radiography systems

Described is a 32-channel CMOS readout front-end for X-ray pixel detectors. This front-end is intended for use in digital radiography systems that employ photon counting methods. In many photon counting systems, counting losses become problematic at higher counting rates. To minimize counting losses and ensure true counts at high rates, a synchronous charge sampling method with analog pipelining has been developed and integrated in standard 3-/spl mu/m CMOS technology. The device operates with a single 5-V power supply and dissipates 4 mW/channel. The equivalent noise charge measured was less than 400 electrons at a counting rate of 8.3 Mcps (with no detector capacitance).