Indirect-ToF system optimization for sensing range enhancement with patterned light source and adaptive binning

An indirect time-of-flight (ToF) system is presented to extend the depth-sensing range. The proposed 4-tap ToF sensor system is equipped with a patterned light source in the transmitter side, focusing the optical power on the selected spot points, maintaining the average optical power compared with the conventional flood-type light source. By focusing the optical power on the spots, the signal-to-noise ratio and demodulation contrast (DC) are enhanced, and the depth noise (precision) performance is improved. The adaptive binning scheme is implemented on the receiver side to decide the optimal binning method according to the amount of ambient light; the DC is used as a metric for this decision. With a proper binning mode selection, the depth performance can be optimized by smaller read noise at the indoor condition, and a larger full well capacity at the outdoor condition. Finally, we achieved a 3.4× working distance increase even under the strong external light conditions.