23.2 A 1.1nW energy harvesting system with 544pW quiescent power for next-generation implants

A wireless sensor that is powered from the endocochlear potential (EP), a 70-to-100mV bio-potential inside the mammalian ear, has been demonstrated in [1]. Due to the anatomical size and physiological constraints inside the ear, a maximum of 1.1 to 6.25nW can be extracted from the EP. The nanowatt power budget of the sensor gives rise to unique challenges with power conversion efficiency and quiescent current reduction in the power management unit (PMU). While [1] presents the system aspects of the biomedical harvesting including the biologic interface and system measurements, this work presents the details of the nanowatt PMU required to power the electronics. More specifically, it focuses on the low-power circuit design techniques needed to realize a nW power converter that is applicable to a broad spectrum of emerging biomedical applications with ultra-low energy-harvesting sources.