Departamento de Física

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https://repositorio.fei.edu.br/handle/FEI/785

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Navegando Departamento de Física por Assunto "Analog-to-Digital Converters"

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    Failure Mechanism and Sampling Frequency Dependency on TID Response of SAR ADCs
    (2021) GONZALEZ, C. J.; COSTA, B. L.; MACHADO, D. N.; VAZ, R. G.; BOAS, A. C. V.; GONÇALEZ, O. L.; PUCHNER, H.; KASTENSMIDT, F. L.; MEDINA, N. H.; Marcilei Aparecida Guazzelli; BALEN, T. R.
    © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.This paper describes the main failure mechanism of charge redistribution Successive Approximation Register (SAR) Analog-to-Digital Converters (ADCs) under radiation. Results of two different radiation experiments (gamma and X-ray) each considering two identical 130nm, 8-bit SAR ADCs, operating with distinct sampling rates, showed that lower sampling frequencies cause the converters to fail at lower accumulated dose, while increasing the sampling frequency increases the converters robustness to radiation. A SPICE model of a SAR ADC is used to simulate radiation induced leakage effects, considering the same technology node and operating conditions of the tested converters. A very good agreement between simulation results and gamma irradiation experimental data allows us to explain the main failure mechanism, which is related to leakage in switches connected to the programmable capacitor array of the internal DAC of the converter.
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    Artigo
    Testing a Fault Tolerant Mixed-Signal Design Under TID and Heavy Ions
    (2021-01-05) GONZALEZ, C. J.; MACHADO, D. N.; VAZ, R. G.; VILAS BOAS, A. C.; GONLALEZ, O. L.; PUCHNER, H.; ADDED, N.; MACCHIONE, E. L. A.; AGUIAR, V. A. P.; KASTENSMIDT, F. L.; MEDINA, N. H.; Marcilei Aparecida Guazzelli; BALEN, T. R.
    © 2021, Brazilian Microelectronics Society. All rights reserved.— 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 vot-ers, besides additional software and hardware resources used for controlling, monitoring and memory manage-ment. 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 occur-ring in one of the voters were also observed. A second heavy ion campaign was then carried out to investigate the voters reliability, comparing the the dynamic cross section of three different software-based voter schemes im-plemented in the considered PSoC.