Progress in Quenching Circuits for Single Photon Avalanche Diodes

An ever wider variety of applications employ Single Photon Avalanche Diodes (SPADs) for the detection of faint optical signals. SPADs are p-n junction biased above the breakdown voltage and operate in Geiger-mode: each electron-hole pair can trigger an avalanche multiplication process that causes the current to swiftly rise to its final value. Additional quenching electronics is necessary for a SPAD proper working. The additional electronics characteristics directly affect the system's obtainable performances. Different quenching circuits affect the detector performances in different ways. In the last 15 years there has been considerable development in the integration of the quenching circuitry directly with the detector, thus leading to improved performances. This paper reviews the state of the art of this evolution, examining and comparing different classes of quenching circuits and explaining their mode of operations, their advantages and disadvantages.