Development of an Eight-Channel Time-Based Readout ASIC for PET Applications

An eight-channel readout ASIC has been developed for reading output signals from solid-state photomultipliers for positron emission tomography applications. This ASIC converts both the signal charge and occurring time to digital timing pulses so that only a time-to-digital converter is required for further signal processing. This provides the advantages of simplified circuit design, reduced power consumption, and suitability for applications that have a large number of readout channels. The ASIC uses a fully current mode preamplifier to achieve high bandwidth (> 100 MHz), high time resolution (better than ~1 ns FWHM), and low power consumption (a few mW/ch). The linear dynamic range of charge measurement is adjustable and can be extended up to 10³ pC. The chip has been fabricated with 0.35 μm 2P4M CMOS technology. A test prototype board has been developed and used for ASIC functionality and performance evaluation. Our preliminary studies show that the targets have been successfully achieved.