Metastability of CMOS latch/flip-flop

Optimal device size, aspect ratio, and configurations for the design of the metastable hardened CMOS latch/flip-flops are obtained by using the AC small-signal analysis in the frequency domain instead of the usual time-domain approach. The Miller effect on the metastability is investigated for the configurations which have a better metastable resolving capability. The mean time between failure (MTBF) was measured, and the result verifies this new design approach. The power supply disturbance and temperature variation effects on the metastability were also measured, and the data show that a 0.75-V change of power supply voltage and 75°C change of chip temperature cause a four orders of magnitude difference in the MTBF. The simulation results using the AC small-signal frequency-domain analysis agree well with the measurement data for the different power supply voltages and chip temperatures, confirming that an AC small-signal approach can be used more widely for the design of metastable hardened latch/flip-flops. The other parameters are discussed in terms of their effects on the latch/flip-flop´s susceptibility to the metastable state