Fully-Integrated Charge Pump Design Optimization for Above-Breakdown Biasing of Single-Photon Avalanche Diodes in 0.13- $\mu$ m CMOS

A design methodology for an area-optimized integrated charge pump is described suitable for on-chip high-voltage reverse bias of single-photon avalanche diodes (SPADs). The high-voltage generation block is implemented in a general-purpose 0.13-μm CMOS process and is capable of generating a maximum regulated output voltage of 17.7 V from an input of 1.8 V. An ON-OFF regulation scheme with dynamic charging and discharging capability of the charge pump provides fast recovery of the output bias voltage during SPAD transients, where overshoot and undershoot must both be corrected during active quench and reset. Following a SPAD avalanche current pulse, the measured transient recovery time is 500 ns from a 150-mV overshoot and a 500-mV undershoot to reach 99% of steady-state output. The implemented SPAD bias generation system occupies 0.175-mm
²
chip area, without requiring an off-chip load capacitor.