3D camera based on linear-mode gain-modulated avalanche photodiodes

In the last few years, both the scientific and industrial communities have shown an increasing interest in range imaging, due to its potential exploitation in various application domains such as robotics, security and surveillance, vehicle safety, gaming, and mobile applications. Among the diversity of techniques available for range detection, Time-of-Flight (ToF) offers advantages in terms of compact system realization, good performance, and low required computational power. The last works on ToF sensors, presenting demodulation sensors based on photon-mixing devices [1, 2], and time-counting sensors based on single-photon avalanche diodes [3], have shown a trend towards higher resolutions, with a consequent reduction of pixel size, higher modulation frequencies, and demodulation contrast to allow better distance precision. In this paper, we introduce a range camera concept that exploits linear-mode avalanche photodiodes (APD) as in-pixel demodulating detectors [4]. Thanks to photocurrent gain modulation, APDs can combine optical sensing and light-signal demodulation in a single device. The main advantage of the APD implementation is the possibility to operate at high frequencies, due to its very wide bandwidth.