Operational Amplifier Characterization at Cryogenic Temperatures

Within the development of the second Deep Underground Neutrino Experiment (DUNE) far detector module, based on the Liquid Argon Time Projection Chamber (LAr-TPC) technology, new solutions for the Photon Detection System (PDS) readout and bias have been proposed. The Vertical Drift (VD) design presents a PDS installed on the cathode plane that is biased at high voltage (300 kV), thus preventing any electrical connection between Silicon PhotoMultipliers (SiPMs), located in the PDS, and the outside of the interface. The chosen solution is to provide power through optical fibers, implementing Power over Fiber (PoF) technology in the field of cryogenic experiments. The optical-to-electrical converters commercially available give an output voltage of a few volts and a step-up converter is needed to provide SiPM with a supply voltage that can be set around 48 V. A boost DC-DC converter has been chosen for the voltage step-up. This solution requires an analog feedback loop control with discrete components working at cryogenic temperatures. This paper presents the characterization of operational amplifiers needed for the analog control scheme. Due to the requirements of the application, quiescent current, offset voltage, offset input current, and bias input current have been measured in function of the temperature, from around 170 K to 330 K. Finally, the measurement uncertainty has been calculated and presented in this paper.