Heavy-Ion Radiation Test on LTC1668 DAC

We measured the heavy ion-induced single-event effect (SEE) susceptibility of the LTC1668 DAC from Linear Technology, to be used in the LiteBIRD JAXA space mission. LiteBIRD will be operated from the Lagrangian L2 in the early 30s, to map the microwave sky with three telescopes equipped with ~ 4800 Transition Edge Sensors (TES) distributed onto three focal planes. The DAC we investigate here is a key item of the detector readout chain since it generates the MHz bias signal that is required by the TES Frequency-Division Multiplexing scheme. This 16 -bit/50 Msps DAC has been identified as a critical element by its output spectral purity and low-power consumption (180 mW), which allow us to fulfil LiteBIRD's power budget constraints. Since this device doesn't exist in a space-qualified version, we have carried out a first characterization campaign at the heavy-ion facility Tandem-ALPI at INFN Legnaro National Laboratory (Italy) for a total irradiation time of ~ 51 hours, to investigate its susceptibility to SEE. We have exposed the device to a beam of different ions with LET values ranging from 12 to 90 MeV cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> mg<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup>. The device is moderately sensitive to SEE, with a threshold LET of 10.3 ± 1.3 MeV cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> mg<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> for SEU, 7.6 ± 2.0 MeV cm mg<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> for SEL, and 9.2 ± 1.95 MeV cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> mg<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> for SET. This first campaign suggests that the use of DAC LTC1668 from space can be seriously considered.