Time-of-Flight (ToF) sensors are precise tools for distance measurement an‎d 3D imaging. These sensors are widely used in various systems, including LiDAR systems for long-range outdoor distance measurements an‎d in more accurate systems for short-range applications in sensitive environments. Among different types of ToF sensors, those based on Single-Photon Avalanche Diodes (SPADs) are considered ideal due to their ultra-high sensitivity to light, single-photon detection capability, an‎d fast response time. SPAD-based ToF sensors can detect individual photons with high accuracy, making them particularly valuable in low-light environments, precision ranging applications, an‎d biomedical imaging. These sensors have a wide range of applications, such as in minimally invasive surgeries, security systems, automotive adaptive cruise control an‎d emergency braking, as well as in computer games an‎d virtual/augmented reality (AR/VR) for motion tracking. Among different ToF architectures, direct ToF sensors using SPADs have become increasingly popular due to their compatibility with modern semiconductor technologies, especially CMOS, enabling low-cost mass production an‎d high temporal resolution. One of the significant advancements in this field is the use of 3D stacking technology, which allows the integration of the photodetector layer with signal processing circuits on a single three-dimensional chip. This approach reduces data transfer delay, enhances timing accuracy, an‎d improves photon detection an‎d processing efficiency. In addition to 3D imaging, ToF measurements are also used in positron emission tomography (PET) an‎d other biomedical techniques involving weak light sources, such as fluorescence lifetime imaging microscopy (FLIM). They are also applied in height measurement, depth sensing, respiration monitoring, image-based ranging, an‎d navigation. However, the proper an‎d rapid operation of SPAD-based ToF sensors depends on the efficient performance of their peripheral circuits, particularly the quenching an‎d recharge circuits. These circuits turn off the SPAD after photon detection an‎d recharge it for the next detection cycle. Without them, the sensorʹs response speed an‎d measurement accuracy would degrade. Therefore, the optimal design of these circuits is essential for maintaining the overall systemʹs accuracy, speed, an‎d efficiency. In this work, we present the design of an active quenching an‎d active recharge (AQAR) circuit. The proposed circuit achieves a photon counting rate of up to 435 MC/S an‎d consumes less than 5.1 µW per megacount per second.

مسعود سيدي

اصغر غلامي , امين مشكات