Charged particle imaging using CMOS Active Pixel Sensors

CMOS Active Pixel Sensors for charged particle imaging are studied. Using same architecture, two prototypes were developed on AMS 0.35 µm OPTO process with different thickness of epitaxial layer. Both have a 32 × 128 pixels array where 24 columns have discriminated binary outputs and 8 columns have test analog outputs. Thanks to the correlated double sampling structure realized in pixel level, noise is well controlled. The temporal noise is around 11 electrons and the fixed pattern noise is below 3 electrons. Charged particle detection performances are evaluated by using a 55Fe radioactive source and measurements are reported. One bit binary output is realized by an auto-zero discriminator which is implemented at the end of each column. The power dissipation of each column is 430 µW (pixel and discriminator).