Patent ID: 11105679

Abstract:
A photodetection circuit includes a single photon avalanche diode (SPAD), and an active quenching circuit coupling the SPAD to an intermediate node and having a variable RC constant. The variable RC constant provides a first RC constant during an idle state so that when the SPAD detects a photon, the SPAD avalanches to begin quenching to set a magnitude of a voltage at a terminal of the SPAD to a quench voltage, the quench voltage being greater than a threshold voltage; a second RC constant greater than the first RC constant during a hold off period during which the quenching occurs so as to maintain the voltage at the terminal of the SPAD at a magnitude that is above the threshold voltage during the hold off period; and a third RC constant less than the second RC constant but greater than the first RC constant during a recharge period during which the SPAD is recharged.