Optimal Determination of Release Time in Integrated Pulse-shaping Circuits for Photon-detection Systems

Silicon photomultipliers (SiPMs), based on Single Photon Avalanche Diodes (SPADs), are widely adopted in photon-detection systems due to their high gain, fast timing response, and CMOS compatibility. In high-background illumination conditions, typical of time-of-flight, fluorescence, and scintillation applications, performance is predominantly limited by background-induced shot noise rather than electronic noise. Mixed-signal SiPMs are proven to be effective in background suppression, while keeping a low power consumption and a low circuit complexity. This work investigates the linear decay of current shaping circuits in mixed-signal SiPMs, providing both an analytical model and a simulation framework to determine the optimal release time of current pulses to maximize the Signal-to-Background-Noise-Ratio. The analytical results are validated through time-domain simulations, demonstrating good agreement and confirming the effectiveness of the proposed methodology in photon-detection systems.