A Multi-Function Radiation-Hardened HV and LV Linear Regulator for SiPM-based HEP Detectors

The use of silicon photomultipliers (SiPMs) to detect light signals in highly radioactive environments presents several challenges, particularly due to their sensitivity on radiation, temperature, and overvoltage, requiring a proper management of their bias supply. This article presents the design and performance of ALDO2, an application-specific integrated circuit and power management solution tailored for SiPM-based high-energy physics detectors. The chip's functions include adjustable and point-of-load linear regulation of the SiPM bias voltage (10-70 V, 50 mA), monitoring of SiPM current, shutdown, over-current and over-temperature protection. The same functions are also available for the low-voltage regulator (1.6-3.3 V, 800 mA), used to generate the power supply of SiPM readout chips that often demand stable and well-filtered input voltages while consuming currents of up to several hundred milliamperes. The chip is intended to operate in radioactive environments typical of particle physics experiments, where it must withstand significant levels of radiation (total ionizing dose and 1-MeV-equivalent neutron fluence in the range of Mrad and 10^14 𝐧_𝐞𝐪/𝐜𝐦^2, respectively). The article provides a comprehensive description of the chip design, as well as experimental measurements, offering insights into the chip's performance under various conditions. Finally, radiation hardening, radiation qualification and reliability are discussed.