Active quenching for single-photon avalanche diode using one- shot circuit

A sensor circuit having a Single Photon Avalanche Diode (SPAD) and an active quenching circuit including a quenching transistor controlled by a one-shot (or similar) circuit is disclosed. The quenching transistor applies a reverse-bias voltage level on the cathode of the SPAD. During photon detection events, pulses generated by the SPAD's avalanche breakdown trigger the one-shot circuit to de-actuate the quenching transistor, allowing the cathode potential to drop below the SPAD's breakdown voltage. After a delay period, which is defined by the one-shot's configuration, allows reliable completion of the avalanche breakdown process, the one-shot circuit re-actuates the quenching transistor such that the SPAD's cathode is refreshed to the reverse-bias voltage level. The one-shot circuit is optionally coupled by way of capacitors to the SPAD and the quenching transistor to facilitate implementation using standard CMOS elements. The sensor is suitable for use in a LIDAR system.