Fast Sensing and Quenching of CMOS SPADs for Minimal Afterpulsing Effects

We present a single-photon avalanche diode (SPAD) front-end circuitry, in a cost-effective 0.35 μm CMOS technology, for single-photon detection in the visible wavelength range, aimed at speeding up the sensing of detector ignition and at promptly quenching the avalanche current buildup. The circuit allows the reduction in detrimental effects of afterpulsing through reducing any delays in the electronics intervention on the detector and through a proper time-varying action of the MOS transistors on the different SPAD's operating conditions. The sensing time is reduced down to a few hundreds of picoseconds, with an active quenching transition of about 1 ns for 6 V excess bias, and a final reset in just 3 ns.