Key challenges for ASIC design and implementation for biomedical imaging

The distinctive challenges for design of read-out ASICs for radiation detectors in biomedical applications originate from the need to be interfaced to detectors with high density of pixels and process photons with high rates. Those two dominant factors impose a range of conflicting restrictions and demands on the design of the readout integrated circuits (ROIC). Some of the key challenges are: limited silicon real estate available per pixel, wide band analog electronics, high digital processing speed and integration with the rest of the system. The read-out electronics for radiation detectors reported in the literature can be classified into four groups regarding the technology and complexity. While the overall complexity increases, the complexity of individual channels is trimmed down as much as possible to accommodate larger number of channels into a limited silicon area. Part of our current work at Monash Centre for Synchrotron Science (MCSS) is the reduction in the likelihood of photons pile-ups and making their detection less erroneous. The pile-up is defined as overlapping of photons that cannot be discriminated. The work is also focused on options for improving output pulse shaping, as a factor relevant for noise reduction and pile-up discrimination.