TID Radiation Characterization of a Commercial High-Speed Delay Line

The Kepler concept proposed by the German Aerospace Center (DLR) intends to drastically improve the performance and robustness of the European Global Navigation Satellite System (GNSS) Galileo. To do so, Kepler relies on ultra-precise optical time transfer and ranging between the satellites of the GNSS constellation. Accuracy down to picosecond-level in time transfer can be reached by employing broadband delay lines in the satellites' electronics. Delay lines are integrated circuits capable of applying a precise and controllable time delay to signals. This class of components is currently not available in space-grade and it is therefore necessary to characterize the behavior of such devices in a radiation environment before considering their usage in orbit. The purpose of this work is to investigate the effects of total ionizing dose (TID) on a commercial high-speed delay line. Co-60 is used as gamma ray source. Total doses of 15 krad in low dose rate and of 300 krad in high dose rate are reached.