Differential Quench and Reset Circuit for Single-Photon Avalanche Diodes

A differential quench and reset (QR) configuration for single-photon avalanche diodes (SPADs) is proposed and investigated in this work. Compared to the traditional single QR configuration in which only one QR circuit is connected to either the cathode or anode of the SPAD, the differential QR configuration consists of two QR circuits to quench and reset through both the cathode and anode terminals. Using a SPAD fabricated in a 65 nm CMOS process, the measurement results of the traditional single passive quench and reset (SPQR) circuit and the proposed differential passive quench and reset (DPQR) circuit shows that the SPAD with the DPQR circuit presented a reduced reset time, an improved timing performance, an increased count rate and a decreased afterpulsing. In addition, the differential output pair from the DPQR circuit has the potential to increase the signal-to-noise ratio of the detection system due to its ability to reject common-mode noise and interference.