A cost-effective modular programmable HV distribution system for photodetectors

In this paper, we present a scalable HV biasing circuit that is able to control 128 channels between FGND and FGND + 125 Volts (with FGND usually at -1800 Volts). The circuit features two boards: a floating HV board that references power and digital signals to a common floating ground (outside of the imaging head), and a HV bias board that houses four 32 channel DAC and a microcontroller elevated to -1800 V. We were able to bias dual PSAPD modules and obtain high quality flood histograms. We measured the ripple of the HV lines to be less than 20 mV RMS.