Self-Restoring and Low-Jitter Circuits for High Timing-Resolution SPAD Sensing Applications

Single-photon avalanche diode (SPAD) imagers have recently emerged in the fields of high-resolution imaging, such as fluorescence lifetime imaging microscopy. This paper presents a new design of passive quenching active reset (PQAR) circuit for high timing-resolution SPAD imagers. The PQAR circuit contains a logic control circuit for self-restoring and dead time reduction in the event of two adjacent incoming photons. Post-layout simulation result shows that the dead time of the sensor has been reduced to 5.46 ns for two adjacent incoming photons, and measurement result shows that the jitter of the photon-induced signal width has been reduced to 63ps. We also present the properties and measurement results of the passive quenching passive reset circuit and the passive quenching active clock-driven reset circuit. Comparison shows that of the three circuits we demonstrate, the PQAR circuit is better suited for the high timing-resolution SPAD imagers.