A Light Detector Capacitance Compensation Technique Achieving Boosted Active Quenching for Single-Photon Avalanche Diodes

The detector capacitance compensation (DCC) technique, which enables double active quenching of single-photon avalanche diode (SPAD), is presented in this article. A well-defined active quenching circuit offers advantages, such as a higher maximum photon-counting rate and lower afterpulsing probability. Also, the adjustable hold-off time caters to various demands in SPAD applications. The fast rise time, contributing to higher jitter performance, enables better resolutions when applied to medical imaging applications, such as positron emission tomography (PET). Meanwhile, the compact design of the active quenching circuit is essential for seamless integration with SPADs. The proposed light active quenching circuit incorporates the conventional active quenching scheme with a light unity-gain amplifier for DCC. The employment of the DCC technique in quenching time simulation demonstrates almost three times better results compared to the conventional approach, with a mere 23% increase in area and lower power consumption. The DCC technique is also effectively applied to a passive quenching circuit. Hold-off time is controlled by only using a current-starved inverter. The simulation results and measured data are shown in this article. Designed circuits are fabricated using 0.18- $\mu $ m complementary metal-oxide–semiconductor (CMOS) technology.