Evaluation of the timing performance of the DIET ASIC

DIET is a 64-channel SiPM readout ASIC for TOF-PET and can measure energy and arrival time independently for each channel. With the increasing requirements for time measurement precision, the timing performance of the DIET chip has been fully evaluated in this paper. The noise sources in the time processing chain, especially in the TDC, were theoretically analysed, and a dedicated test system was built. The time jitter of the analogue front end and the TDC were measured and analysed. The test results show that the total jitters of the analogue front-end and the TDC are 24 ps and 22 ps RMS at 50 p.e. input signal, respectively. The percentages of the contribution by INL, thermal noise, and quantization noise of the TDC are 70%, 16.6%, and 13.4%, respectively. The DIET chip was also tested with SiPM and LYSO detectors. A CRT resolution of 244 ps FWHM was achieved using two single 3 x 3 x 16 mm3 crystals.