Active quenching circuit with adjustable reverse bias voltage for single photon avalanche diodes arrays

In this paper, a quenching circuit architecture, where the reverse bias voltage is adjustable, was proposed to deal with the non-uniform breakdown voltages of single-photon avalanche diode (SPAD) linear arrays. A global resistor string digital-to-analog converter (DAC) was applied in this architecture to provide an optional potential for the anode of SPAD. Adjusting the anode voltage of SPAD according to its breakdown voltage can guarantee each detector in the array with similar excess bias voltage. The bias voltage of each pixel is adjustable from 0 to 2V with the step length of 62.5mV. Also, based on the reverse bias voltage regulation circuit, a novel active quenching circuit was designed, which can quickly quench the avalanche process, and simulated in the 1×128 SPAD readout circuit for further verification. The SPAD array was fabricated in SiC technology and the quenching and readout circuit was fabricated in TSMC 0.18-μm CMOS technology. The whole 1×128 SiC SPAD arrays and circuits were packaged by gold wire bonding. The measurements show that the SPAD array can realize avalanche detection and quenching, moreover the dark count uniformity of array SPADs can be significantly improved.