Ph.D Thesis


Ph.D StudentEshkoli Ayal
Subject3D CMOS Imaging based on Si Photomultiplier
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROFESSOR EMERITUS Yael Nemirovsky


Abstract

Among advanced electronic designs, electro-optical systems based on CMOS image sensors perhaps have undergone the most dramatic technological revolutions of the last decades. Recently, a new family of vision systems has emerged aimed at three-dimensional (3D) sensing and applied as optical radars.  In particular, there is a high demand for LiDARs (Light Detection and Ranging) for advanced driver-assistance systems (ADAS), consumer applications, such as gaming, augmented, and virtual realities (AR/VR), and other human-machine interfaces.


This research focuses on the study of CMOS Silicon Photomultiplier (SiPM) - a novel solid-state sensor closely related to SPADs (single photon avalanche diode in Geiger Mode) as the building block for innovative depth sensing. The simplest description of the SPAD is a binary photon-activated "switch" that counts digitally single photons, at a sampling time interval determined by its dead-time (approximately 20 nsec). SPAD sensors are the most sensitive silicon based solid state optical sensors. However, during recovery, the SPAD cannot detect other photons. Hence, arrays of CMOS-SPAD Geiger mode sub-pixels, which are electrically combined in parallel and are known as CMOS Silicon Photomultiplier (SiPM), overcome this limita?tion enabling photon-counting as well as photon-timing. The CMOS SiPM readout circuitry requires advanced mixed signal design, where digital signals are combined analogically, and the timing of these signals is then measured digitally.