Abstract

CRIADO CRUZ, Dilaila; VEGA GOMEZ, Leonardo César; PAVONI OLIVER, Sonnia  and  ESCARTIN FERNANDEZ, Víctor E.. Metastability analysis of two stages synchronizer synthesized in FPGA Cyclone III and Cyclone V. EAC [online]. 2021, vol.42, n.1, pp. 34-44.  Epub May 17, 2021. ISSN 1815-5928.

Metastability is a probabilistic phenomenon that causes failures in digital systems. It most likely occurs when a circuit receives an asynchronous signal or signals are exchanged between synchronous circuits with unrelated clock domains. To reduce the risk of metastability spreading across a circuit, it is recommended to use synchronizers. The effectiveness of synchronizers can be expressed by means of the MTBF (Mean Time Between Failure) parameter. Furthermore, the technological development that has allowed the decrease of CMOS devices dimensions towards nanometer scale, favors the appearance of effects that impact metastability. It is necessary that electronic circuits designers know such risks and take actions to reduce them. This work aims to analyze the behavior of metastability in two-stage synchronizers developed on Intel-Altera FPGA, Cyclone III (65 nm) and Cyclone V (28 nm) families. Critical conditions in the industrial temperature operation range, based on the risk of metastability and reliability criteria, were determined. The MTBF of synchronizers varied with the operating temperature and did so differently for each technology. In Cyclone III, a change in behavior was observed at -40 °C, probably due to inverted temperature dependence (ITD). For Cyclone V, ITD was observed over the whole industrial temperature range.

Keywords : metastability; FPGA; synchronizers.

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