CMOS-Compatible Time-of-Flight 3D Imaging Sensors and Systems

Abstract

This paper describes the operation principle of Time-of-Flight (ToF) sensors and systems for 3D imaging. It starts with an overview of the simplest ToF sensors formed by traditional photogate and pinned photodiode pixels readily available in a standard CMOS process. The performance limitations of such pixels are explained, leading to more advanced sensor structures such as the current assisted photonic demodulator (CAPD) and gate assisted photonic demodulator (GAPD), wherein both use an electric field to guide carriers and achieve a more effective signal modulation. To overcome the tradeoff between modulation contrast and power consumption for mobile ToF applications, a junction assisted photonic demodulator (JAPD) pixel architecture is proposed and experimentally demonstrated. Finally, the design of the readout circuit of a ToF pixel is discussed.