Quenching circuit using HV transistors

This thesis presents the design and optimization of a quencher circuit for Single-Photon Avalanche Diodes (SPADs) fabricated in a 0.35-μm high-voltage CMOS process, aimed at improving the performance of SPAD-based photon detection systems. SPADs, known for their ability to detect single photons, are crucial in applications such as Time-of-Flight (ToF) sensors, quantum cryptography, and optical communication. A major challenge in SPAD operation is managing the avalanche process, which requires rapid quenching to prevent diode damage and ensure accurate photon detection. The proposed quenching circuit incorporates high-voltage transistors specifically chosen to optimize reset times and maximize photon detection efficiency. The design was fine-tuned to minimize afterpulsing and ensure stable operation across varying conditions. Pre-layout simulations in Cadence Virtuoso confirmed the circuit’s ability to achieve precise timing optimization and voltage transitions, crucial for reliable photon detection. Post-layout simulations, accounting for parasitic effcts, demonstrated robust performance despite process variations. The final design achieves improved response and passive quenching times, outperforming conventional circuits and similar works in reducing afterpulsing. This work significantly advances SPAD-based systems, enhancing photon detection efficiency and reliability for demanding optoelectronic applications.