Fast timing SiGe BiCMOS monolithic silicon pixel ASIC for HEP and medical imaging

As High-Energy Physics (HEP) experiments push the boundaries of fundamental physics, the demand for improved time-resolution detector systems increases. Fast timing detectors with a resolution of 10 ps are essential for accurately identifying and reconstructing particle trajectories in high-collision rate environments, such as the Large Hadron Collider (LHC) at CERN. This Ph.D. thesis presents the development of two monolithic silicon pixel sensor demonstrators, focusing on the design and optimization of a SiGe HBT-based front-end architecture implemented in a 130 nm SiGe BiCMOS process. This architecture is adaptable for two distinct applications, highlighting its versatility in addressing different requirements. The first demonstrator targets sub-20 ps timing resolution tailored for low-power and fast-timing applications in HEP, medical imaging, and space-borne instruments, as part of the MONOLITH H2020 ERC advanced project. The system integrates a monolithic sensor designed with hexagonal pixels of 50 µm pitch, capable of sub-20 ps timing performance based on simulations conducted in the Virtuoso framework. This prototype features in-pixel electronics, with the front-end operating at a supply voltage of 1.2 V and a current of 50 µA. The second demonstrator involves adapting the aforementioned front-end for the 100µPET project, aimed at constructing a next-generation small-animal PET scanner for ultra-high resolution molecular imaging of atherosclerosis in ApoE-/- mice. This project emphasizes on a low-power, low-mismatch optimization of the in-pixel front-end and discriminator circuit. This circuit operating at 12.5 µW/channel achieves an Equivalent Noise Charge of 200 e^{-}. The pixel-to-pixel charge threshold mismatch dispersion can be mitigated by a 3-bit pixel-level DAC. The front-end achieves a time jitter of 200 ps offering sufficient time resolution to improve event reconstruction reducing false coincidences. The circuit is integrated into a 2.3 cm x 3.0 cm monolithic pixel sensor with a 132x192 hexagonal pixel matrix (150 µm^{2} area). The thesis concludes with an exploration of the challenges and future directions for fast-timing detectors in HEP and medical imaging, underscoring the potential of the developed ASICs to advance these fields.