Functional verification schemes at a level different from component-level testing are emerging as a cost-effective tool for those space systems for which the risk associated with a lower level of assurance can be accepted. Despite the promising potential, system-level radiation testing can be applied to the functional verification of systems under restricted intrinsic boundaries. Most of them are related to the use of hadrons as opposed to heavy ions. Hadrons are preferred for the irradiation of any bulky system, in general, because of their deeper penetration capabilities. General guidelines about the test preparation and procedure for a high-level radiation test are provided to allow understanding which information can be extracted from these kinds of functional verification schemes in order to compare them with the reliability and availability requirements. The use of a general scaling factor for the observed high-level cross sections allows converting test cross sections into orbit rates.

Testing at system level is evaluated by measuring the sensitivity of point-of-load (PoL) converter parameters, submitted to total ionizing dose (TID) irradiations, at both system and component levels. Testing at system level shows that the complete system can be fully functional at the TID level more than two times higher than the qualification level obtained using a standard-based component-level approach. Analysis of the failure processes shows that the TID tolerance during testing at system level is increased due to internal compensation in the system. Finally, advantages and shortcomings of the testing at system level are discussed.

System-level radiation testing of electronics is evaluated, based on test examples of the System-in-Package (SiP) module irradiations. Total ionizing dose and single event effects tests are analyzed to better understand the opportunities and limitations of the system-level approach in the context of the radiation qualification of electronics. Impact on the SiP product development is discussed.

Power cycling of a point-of-load converter is observed during system-level heavy ions tests. This event has low cross section and is observed for reduced supply voltage of the device under test. Laser tests are used to reproduce this effect and show that it might be due to propagation of single-event transients from the voltage reference to the operational amplifier being part of the undervoltage protection circuit. Laser tests show that propagating transients are the ones with a high enough positive peak and an insignificant negative peak value, whereas some transients with a bigger maximum and/or peak-to-peak value do not propagate. SPICE simulation shows that in an operational amplifier with low voltage difference between V ⁺ and V ^- , there is a difference in the propagation of unipolar and bipolar transients from the input to the output of the amplifier. Analysis of the voltage-controlled current source in the amplifier also explains the difference in propagation of bipolar transients with a negative peak followed by a positive peak and with a positive peak followed by a negative peak.

We present and analyze system-level total ionizing dose (TID) tests of the simple analog system, point-of-load DC/DC converter from 3D-Plus, which was already qualified up to 50 krad(SiO ₂ ) based on component-level tests. TID response varied with the radiation facility for several parts; however, extensive testing with one part have shown significant differences in the TID level of functional failure observed for different operation modes (configurations): depending on the operating configuration of the device, the observed TID level of failure varies from about 60 krad(SiO ₂ ) to more than 400 krad(SiO ₂ ). These differences are depicted with use of the safe operating area (SOA) plot for the system, which incorporates main system functional parameters. We also explore the potential utilization of the SOA concept in defining the system’s TID performance, employing a range of TID thresholds rather than relying on a singular value.

A system-level total ionizing dose test method of satellite subsystems is discussed in the context of the radiation qualification of a satellite. System-level tests are performed with high-energy X-rays, and the irradiation results of the key subsystems, including the on-board computer, attitude- and orbit-control-system computer, and battery management system, are presented and analyzed in terms of the repeatability of the results, the observability issues, and the importance of the test conditions. Furthermore, the main benefits of the system-level total ionizing dose tests of the given subsystems are discussed, as well as the risks related to performing tests at the system level.