Radiation Effects on SRAM-Based FPGAs

The past 30 years have seen the discovery that electronic circuits are sensitive to transient effects such as Single Event Upsets (SEUs) provoked by ionizing radiation [1]. Since the discovery of SEUs at aircraft altitudes, researchers have made significant efforts to monitor the environment. The space and the earth environment contain various ionizing radiations, generated by natural phenomena such as sun activity and manmade radiation that interacts with silicon atoms. If, at ground level, neutrons and alpha particles are the most frequent causes of SEUs, in a space environment, they are protons and heavy ions. When a particle hits the surface of a silicon area, it loses its energy through the production of free electron-hole pairs, resulting in a dense ionized track in the struck region [2]. Interestingly, when the struck silicon area implements a static memory cell, the transient pulse may induce permanent changes: it can indeed activate the inversion of the stored value. In SRAM-based FPGAs, transient faults originating in the FPGAs configuration memory have dramatic effects since the circuits the FPGAs implement are totally controlled by the content of the configuration memory, which is composed of static RAM cells [3, 4]. In this chapter, the effects of the SEUs within the configuration memory of SRAM-based FPGAs will be accurately described, thanks to the graph model presented in the previous chapter, the effects of SEUs within the internal FPGA’s resources is modeled and analyzed.