Characterization of Single-Event Transients in Schmitt Trigger Inverter Chains Operating at Subthreshold Voltages

Single-event transients (SETs) induced by alpha particles and heavy ions are measured and analyzed with subthreshold voltage SET characterization circuits. Using a Schmitt trigger inverter target chain fabricated in a 65-nm bulk CMOS process, SET pulse widths are captured from an operating voltage down to 0.32 V. At nominal voltages, the Schmitt trigger inverter chain is immune to SETs, but at subthreshold voltages energetic particles can induce SET pulse widths that range up to and over a microsecond. Additionally, the results show that at subthreshold voltages the 28-nm node offers a significant improvement in the SET response over the 65-nm node.