Toward a 2D high-performance multi-channel system for time-correlated single-photon counting applications

Time-Correlated Single Photon Counting (TCSPC) is acknowledged as one of the most effective techniques for measuring weak and fast optical signals, since it provides very high temporal resolution and sensitivity. Nevertheless, the long acquisition time needed to perform a measurement it's still the main drawback. To overcome this limitation, multidimensional TCSPC systems have been developed, but they still suffer for a strong trade-off between performance and number of channels: the higher the number of channels, the poorer the performance. In this work we present the design of a complete TCSPC acquisition system which is meant to overcome this trade-off. Since the best state-of-the-art detectors and sensing circuits developed so far are designed with different technologies, following the same approach those circuits will be designed onto different chips to achieve the best performance from both sides. Through Silicon Vias (TSVs) will be investigated as a possible solution for connecting a custom technology SPAD array to a CMOS pick-up circuit. Since a high number of detectors will cause the count rate to saturate due to the limited transfer rate of a PC, the target throughput has been set to 10 Gb/s, well beyond the state of the art. Consequently, the number of acquisition chains has been tailored on the affordable throughput, and a dynamic-routing logic connects the detectors to this lower number of acquisition channels. Five fast Time-to-Amplitude Converters (TACs), able to reach 80 Mconv/s, have been designed to get high temporal resolution along with low dead time.