A ring-oscillator-based active quenching and active recharge circuit for single photon avalanche diodes

This paper proposes a new active quenching and active recharge circuit for single photon avalanche diodes (SPADs). Thanks to the simple ring oscillator architecture, the circuit is one of the most compact active quenching circuits published in the literature. Additionally, a simple modification to the basic version of the circuit allows to measure the hold-off delay and the recharge pulse width without any high-speed time interval measurement electronics by configuring the circuit as a free-running ring oscillator which can be used for testing purposes and for implementation of a hold-off delay control. A test chip has been fabricated in a standard 0.13 mum CMOS technology and simulations and experimental results are reported.