Design and characterization of the ePix100a: A low noise integrating pixel ASIC for LCLS detectors

ePix100 is the first variant of a novel class of integrating pixel ASICs architectures optimized for the processing of signals in second generation LINAC Coherent Light Source (LCLS) X-Ray cameras. ePix ASICs are based on a common platform composed of a random access analog matrix of pixel with global shutter, fast parallel column readout, and dedicated sigma-delta analog to digital converters per column. The ePix100 variant is optimized for low noise application requiring high spatial resolution and fast frame rates. The ASIC has pixels of 50×50 μm² size arranged in a 352×384 array, a resolution of 50e^- r.m.s., and a signal range of 35fC (100 photons at 8keV). In its final version it will be able to sustain a frame rate of 1 kHz. Currently a full-size analog version, ePix100a, has been fabricated in TSMC CMOS 0.25 μm technology. The ePix100a has been fully characterized and results are here reported.