US Patent 9997551 Spad array with pixel-level bias control

A sensing device includes an array of sensing elements. Each sensing element includes a photodiode, including a p-n junction, and a local biasing circuit, coupled to reverse-bias the p-n junction at a bias voltage greater than a breakdown voltage of the p-n junction by a margin sufficient so that a single photon incident on the p-n junction triggers an avalanche pulse output from the sensing element. A bias control circuit is coupled to set the bias voltage in different ones of the sensing elements to different, respective values that are greater than the breakdown voltage.