A 2.5 mW/ch, 50 Mcps, 10-analog channel, adaptively biased read-out front-end IC with 9.71 ps-RMS timing resolution for single-photon time-of-flight PET applications in 90 nm CMOS

Abstract

A 10-channel time-of-flight (TOF) positron emission tomography (PET) IC that uses a digital-to-analog (DAC) - based architecture is implemented in 90nm CMOS process. The DAC is used to compensate for timing resolution variation attributed to amplifier gain fluctuation. Mixed-signal reset signals enhance photon counting speed achieving 5M counts/s/ch. The IC uses adaptive biases to stabilize the gain of preamplifiers and comparators. Multi-stage preamplifiers and comparator architectures were selected for low power. Measurement results show that these techniques enable the IC to achieve 9.71ps-RMS of intrinsic jitter and 181.5ps-FWHM (Full-width-at-half-maximum) timing resolution using an avalanche photo-diode and laser setup while consuming 2.5mW at 0.5V and 1.2V power supplies. The IC was fabricated in a 90nm CMOS process with area of 3.3 × 2.7mm2.