BASIC64: A new mixed-signal front-end ASIC for SiPM detectors

In the framework of the INSIDE (INnovative Solutions for Dosimetry in hadrontherapy) project, a CMOS multichannel front-end ASIC, BASIC64, has been developed for interfacing the SiPM sensors used in a PET system aimed to detect the back-to-back γ’s produced by the interaction of the beam with the body tissue. The ASIC hosts 64 current-mode front-end channels, generates an accurate trigger signal corresponding to the detection of a valid event and provides the associated energy information in the digital domain, by means of a 10-bit integrated ADC. The main simulated performance parameters include a time resolution of 300ps FWHM and a dynamic range of about 400pC, corresponding to 2500 photoelectrons for a SiPM gain of 106, achieved with a total power consumption of approximately 10mW/channel. The signal to noise ratio of the front-end is around 20dB for signals generated by a single photoelectron, i.e. a single SiPM micro-cell fired, which allows setting very low threshold levels and achieving good time resolution. With a 5MHz ADC clock frequency, full read-out and A/D conversion of all the 64 channels requires about 13.4μs, thus the sustainable rate for events which involve all the ASIC channels is 75kHz.