Supply Voltage Dependency on the Single Event Upset Susceptibility of Temporal Dual-Feedback Flip-Flops in a 90 nm Bulk CMOS Process

In this paper we investigate the efficiency of using temporal and spatial hardening techniques in flip-flop design for single event upset (SEU) mitigation at different supply voltages. We present three novel SEU tolerant flip-flop topologies intended for low supply voltage operation. The most SEU tolerant flip-flop among the proposed flip-flop topologies shows ability of achieving maximum SEU cross-section below 1.9 ·10-10cm2/bit (no SEUs detected) at 500 mV supply voltage, 4 ·10-10cm2/bit at 250 mV supply voltage, and 2 ·10- 9cm2/bit at 180 mV supply voltage. When scaling the supply voltage from 1 V down to 500 mV, 250 mV and 180 mV, the proposed flip-flops achieve at least - 72%, - 92.5% and - 95% (respectively) reduction in energy per transition compared to a Dual Interlocked Storage Cell based flip-flop when operated at a supply voltage of 1 V. The flip-flops have been designed and fabricated in a low-power commercial 90-nm bulk CMOS process and were tested using heavy ions with LET between 8.6 MeV-cm2/mg and 53.7 MeV-cm2/mg.