Fast Cascoded Quenching Circuit for Decreasing Afterpulsing Effects in 0.35- $\mu$ m 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- ${\mu }\text{m}$ 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 ${\mu }\text{m}$ . 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.