Quantum film direct time of flight sensor circuit for low cost short wave infrared operation

Abstract

A time-of-flight system includes an emitter-circuit generating and directing pulses of light toward a target, and a receiver-circuit including a photodetector coupled between a bias node and a sensing node to detect pulses that have reflected off the target, a comparison circuit comparing a sense voltage at the sensing node to a reference, a timing measurement circuit measuring elapsed time between generation of a given pulse and detection thereof after reflection off the target, and a programmable current sink that sinks a current from the sensing node equal to a portion of a photocurrent generated by the photodetector due to detection of ambient light. A timing-generation circuit synchronizes generation of the pulses and measurement of elapsed time by the timing circuit. A processor adjusts a magnitude of the current sunk from the sensing node based upon output of the comparison circuit when the emitter circuit is deactivated.