A Regulated High Negative Voltage Generator for Single-Photon Avalanche Photodiodes

In this work, a regulated high negative voltage generator for biasing single-photon avalanche photodiodes (SPAD) was developed. The circuit provides up to -70 V from a positive voltage source. This circuit allows users to control the negative output voltage using a positive voltage rail, thus eliminating the requirement of a negative voltage for the negative voltage control. This approach simplifies the setting of the output and facilitates integration in miniaturized photon counting systems. The testing on a fabricated PCB of this circuit show that the output voltage can be accurately controlled up to -70 V with ripples of less than 80 mV. A SPAD based experimental setup was also built and the experimental results show that the circuit is able to maintain a stable bias voltage for a planar SPAD at both low and high counting rates.