A Low-Power 8×8 SiPM Readout ASIC With Row-Column Summing Structure for Compact TOF-PET Detectors

A new low-power 64-channel Front-End application-specific integrated circuit (ASIC) for the readout of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$</tex-math> </inline-formula> Silicon photomultiplier (SiPM) Arrays (FESA) with a row-column summing structure is proposed for flexibly building a compact and cost-effective time-of-flight (TOF) positron emission tomography (PET) system. The inputs from the SiPM array are picked up individually and row-column summed to reduce the number of measurement circuits and overall power consumption. An energy-to-time conversion circuit based on the delayed linear discharge method is proposed with high linearity and enhanced small-signal measurement ability, which allows FESA to use a fully time-based readout strategy so that a simple and robust interface for system-level integration is provided. Fabricated in 180 nm CMOS technology, FESA has been evaluated with an intrinsic timing jitter of 11.8 ps, a dynamic energy measurement range of 44 dB, a power consumption of 2.39 mW per channel, and an event rate of 4 MS/s. With an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$</tex-math> </inline-formula> Hamamatsu S13361-3050 SiPM array 1:1 coupled to an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$</tex-math> </inline-formula> lutetium yttrium oxyorthosilicate (LYSO) crystal array, the FESA-based detector exhibits a coincidence time resolution (CTR) of 237 ps FWHM and an energy resolution of 12.6%. The measured flood image with an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$</tex-math> </inline-formula> SiPM array 1:9 coupled to a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$24\times 24$</tex-math> </inline-formula> LYSO crystal array demonstrates the ability of FESA to decode a crystal size of 1 mm. The test results show that FESA is a promising candidate for the future construction of high-performance and high-integration TOF-PET systems.