A multipurpose monolithic array of 2×2 multi-channel digital silicon photomultipliers (MD-SiPMs) fabricated in 40nm CMOS technology is presented. Each MD-SiPM comprises 64×64 smart pixels connected to 128 low-power 45ps sliding-scale time-to-digital converters (TDCs). The MD-SiPMs are designed to indirectly capture gamma events in positron emission tomography (PET). The sensor can operate in frame-based and event-driven mode; the latter best suited to capture gamma events. The digital read-out is fully embedded in the sensor and it is reconfigurable by way of serial communication. Data packets are sent following a simple protocol compatible with an external FIFO, therefore eliminating the need of an FPGA. A dedicated input can be used to operate synchronously with an event generator, such as a pulsed laser, useful in other applications, like LiDAR. The system is inherently compatible with 3D-stacking technology; thus serving as a front end for different SPAD technologies, suitable for a variety of applications.

A multipurpose monolithic array of 2 × 2 multichannel digital silicon photomultipliers (MD-SiPMs) fabricated in 40-nm CMOS technology is presented. Each MD-SiPM comprises 64 × 64 smart pixels connected to 128 low-power 45-ps sliding-scale time-to-digital converters (TDCs). The system can operate in two different modes: 1) event-driven and 2) frame-based. The first is suited for positron emission tomography (PET) and the second for synchronous applications like LiDAR. The design includes electronics to capture gamma events by means of a scintillator. The digital readout is fully embedded in the sensor and it is reconfigurable by SPI. Data packets are sent following a simple protocol compatible with an external FIFO, therefore making use of an FPGA optional. Every MD-SiPM can deliver up to 64M time-stamps/s. The sensor can be arranged in any type of configuration through a dedicated synchronization input and can be used to operate jointly with an event generator, such as a pulsed laser, which is useful in many applications. Inherently compatible with 3-D-stacking technology, the sensor can serve as front-end electronics when it is used with a different SPAD silicon tear.

In time-of-flight (TOF) positron emission tomography (PET), the coincidence resolving time (CRT) has a strong influence on the overall performance. Multichannel digital silicon photomultipliers (MD-SiPMs) are able to obtain several timestamps for gamma photon timemark estimation. Using this feature, the CRT is improved and the system robustness is significantly increased by utilizing multiple photoelectron timestamps. In addition, the PET instrumentation chain is simplified because of the intrinsic digitization and integrated functionality of the MD-SiPM. The main objective of this work is to demonstrate the possibility of building a complete highly-miniaturized PET detector module for endoscopic applications. In addition, we show that it's possible to operate simultaneously several MD-SiPM array chips in order to build a small-animal PET detector modules. We present the implementation of two PET detector modules that are based on MD-SiPMs: a small animal and an endoscopic PET detector modules. The small animal PET detector module consists of 2×4 monolithic MD-SiPM array chips. In addition, this module includes a low-cost field programmable gate array (FPGA), a temperature controlling system and data transfer interfaces. The endoscopic PET detector module comprises a single monolithic array of 9×18 MD-SiPM and a small form-factor FPGA. In this module, a remarkable level of compactness is achieved. Eventually, a thermal characterization and a preliminary radiation measurement are presented.