Abstract
A compact single-photon avalanche diode (SPAD) testing array fabricated in standard 0.18μm CMOS technology is presented. Four types of SPAD are designed in 18μm pixel pitch with 3μm active region and arranged in four 16×30 sub-arrays. The implemented column readout circuit consists of column-shared comparator and tunable hold-off time control circuit, which performs the avalanche sensing with feedback loop to achieve the active recharge operation without complex in-pixel circuitry. With the implemented active feedback path for SPAD reset operation, the maximum count rate is improved with reduced after-pulsing probability (APP). By means of the proposed architecture, the statistical performance of dark count rate (DCR), photon detection efficiency (PDE), and photon response are presented and discussed. The SPAD-based imaging platform successfully demonstrates captured images with photon shot-noise-limited performance.