Testing a Fault Tolerant Mixed-Signal Design Under TID and Heavy Ions

Abstract

This work presents results of three distinct radiation tests performed upon a fault-tolerant data acquisition system comprising a design diversity redundancy technique. The first and second experiments are Total Ionizing Dose (TID) essays, comprising gamma and X-ray irradiations. The last experiment considers single event effects, in which two heavy ion irradiation campaigns are carried out. The case study system comprises three analog-to-digital converters and two software-based voters, besides additional software and hardware resources used for controlling, monitoring and memory management. The applied Diversity Triple Modular Redundancy (DTMR) technique, comprises different levels of diversity (temporal and architectural). The circuit was designed in a programmable System-on-Chip (PSoC), fabricated in a 130nm CMOS technology process. Results show that the technique may increase the lifetime of the system under TID if comparing with a non-redundant implementation. Considering the heavy ions experiments the system was proved effective to tolerate 100% of the observed errors originated in the converters, while errors in the processing unit present a higher criticality. Critical errors occurring in one of the voters were also observed. A second heavy-ion campaign was then carried out to investigate the voters reliability, comparing the dynamic cross-section of three different software-based voter schemes implemented in the considered PSoC.