40nW subthreshold event detector chip for seismic sensors

Unattended ground sensors (UGS) are widely used for persistent, surveillance that detects potential threats from intruders without generating false alarms. Seismic sensors are used to catch vibrations produced by intruders. Battery life is the limiting factor for solutions using digital processing. Thus power management strategies need to be employed to ensure longevity of the sensor networks. A 40nW subthreshold analog CMOS (complementary metal oxide semiconductor) is fabricated and tested, that wakes up a threat classifying stage. The system architecture is proposed along with optimizations for the different stages of the system. Variations in the subthreshold system will be discussed resulting in different system responses.