Fault Tolerant Flip-flop Design for Ultra-low Powersubthreshold Logic: Design and Analysis

Low power consumption and radiation hardness aregenerally competing requirements for spaceelectronics as well as many earth-bound highreliability applications. Recently, subthresholdlogic has emerged as a technology that can deliverthe theoretical minimum energy per computation byrunning at ultra-low levels. The resultingperformance degradation is tolerable due the dramaticincrease in energy efficiency. However, operatingcircuits at such low voltages decreases the criticalcharge - Qcrit - required to corrupt the contents ofmemories and sequential elements. The marriage ofsubthreshold logic and high-reliability electronicsis inevitable, yet there has been to date noinvestigation of the effects of radiation on circuitsthat operate at such low voltages. This book provides a comprehensive comparison of a variety oftraditional flip-flop designs at subthreshold levels- not just in terms of performance, power and areabut radiation hardness as well. Furthermore, a novelflip-flop design is presented, which is optimized forrobust subthreshold operation.