Fast Cascoded Quenching Circuit for Decreasing Afterpulsing Effects in 0.35-μm CMOS

In this letter, we present a fully integrated single-photon avalanche diode (SPAD) using a fast cascoded quenching circuit (QC) fabricated in a 0.35-mu m CMOS process. The QC features a fast active quenching time of only 0.48 ns and an adjustable total dead time (9.5-17 ns) to further reduce afterpulsing effects. To prove the quenching performance, the circuit was integrated together with a large-area SPAD having an active diameter of 80 mu m. Experimental verification of reduction of afterpulsing with early quenching is shown. Thus, a minimal afterpulsing probability of 0.9% was measured at 6.6 V excess bias and a photon detection probability of 22% at a wavelength of 850 nm was achieved.