Single-Event Effect Mitigation in RTAX-DSP Spaceflight FPGAs
When high-energy ions present in space strike the substrate of an IC, their impact can cause momentary current/voltage pulses in the IC’s circuitry. When these pulses are sufficient to change the data on the circuit, they are referred to collectively as single-event effects (SEEs). Two subclasses of SEEs were of particular interest to the designers of RTAX-DSP:
Single-event upsets (SEUs): SEUs are probably the best understood class of SEEs. An SEU occurs when sufficient charge is collected in a static memory element (latch, register or SRAM cell) that the resulting voltage causes the static memory element to change state (flip its bit). These errors or upsets last until the next time new data is written to the memory element.
Single-event transients (SETs): When impacting ions induce voltage pulses on combinatorial circuitry in a device, these effects are known as SETs. If the induced voltage level exceeds that of the switching threshold and is of sufficient pulse-width, erroneous data values can be propagated through the circuit. As the name implies, these errors are temporary in nature, with pulse-widths on the order of 500 ps.
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Tags: Actel