SET propagation in micropipelines

Radiation-induced Single Event Transients (SETs) have the potential to create metastability in asynchronous circuits, as they are much shorter than the typical handshake cycle and do not respect the timing closure. Micropipelines have been shown to be effective in filtering those pulses. In this paper 1 we investigate the propagation of pulses of critical width through a micropipeline in SPICE simulations. We study how the pipeline implementation, especially the output buffer design (matched threshold, high threshold, Schmitt-trigger) influences the propagation behavior. For the solutions with single sided thresholds we observe a considerable propagation potential of critical pulses that strongly depends, however, on the degree of threshold matching. The Schmitt trigger output, in contrast, reliably filters all pulses which are shorter than a certain threshold while propagating all others securely. At the same time our respective analysis reveals that the cost of the Schmitt trigger stage in terms of performance overheads is also significant, so the choice needs to be carefully balanced with the application requirements.