A self-triggered CMOS front-end for Silicon Photo-Multiplier detectors

A complete analog front-end channel suitable for Silicon Photo-Multiplier (SiPM) detectors has been designed in a standard CMOS 0.35 mum technology. The current-mode approach exploited in the first stage of the proposed architecture allows to fulfill the severe constraints imposed by this kind of detectors in terms of dynamic range and speed of operation, without excessive power consumption. Timing accuracy of about 50 ps, obtained with the electronics coupled to a fast pulse generator in series to a charge injection capacitance, has been obtained by means of a fast current discriminator. The circuit is specially intended for medical imaging applications, for instance PET, but programmability of detector bias, gain and threshold current enhances the flexibility of the architecture, making it suitable for different kind of SiPM detectors and applications. An 8-channel ASIC, suitable for the read-out of SiPM arrays has been designed and manufactured following this approach. The characterization of the chip is currently in progress. Here we report the preliminary measurement results obtained by coupling a single channel to a single SiPM detector excited by a pulsed blue LED.