Design of a Scalable Modular Bias Voltage Supply With Reduced Noise for Multi-Channel SiPM Readout

This work presents the design and characterization of a modular, digitally programmable Voltage Supply Unit (VSU) optimized for Silicon Photomultiplier (SiPM) arrays in high-sensitivity applications such as cryogenic particle detectors. The proposed VSU combines a flyback converter with a cascaded linear regulator and an SPI-controlled (Serial Peripheral Interface) Digital-to-Analog Converter (DAC) reference. A set of passive and active noise mitigation strategies, including snubber networks, common-mode filtering, and careful layout design, enables sub-millivolt peak-to-peak noise up to 200 V DC output. Each module provides galvanic isolation, per-channel programmability, and low output current, making it suitable for scalable, low-background SiPM-based detectors. Experimental results demonstrate a peak-to-peak noise of less than 1mVpp at 200 V and 2 mA, corresponding to SiPM gain fluctuations below 0.1%, with a Signal-to-Noise Ratio (SNR) higher than 80 dB and a programming resolution of 3.1 mV. A comparison with commercial and custom systems confirms competitive performance at reduced cost and form factor. The novelty of this approach lies in combining low-noise design, digital control, and modularity using discrete components, making the VSU suitable for use in large-scale systems, where stable, channel-isolated high-voltage biasing is required.