A single-inductor AC-DC piezoelectric energy-harvester/battery-charger IC converting ±(0.35 to 1.2V) to (2.7 to 4.5V)

Energy harvesting in microscale devices is important (because space constrains energy) and challenging (because rectifying small ac piezoelectric signals is lossy and difficult). The 1 mm² 2 ¿m BiCMOS piezoelectric energy harvester-charger IC presented harnesses up to 30 ¿W from a PZT transducer's ±0.35-to-1.2 V levels to charge 1.2-to-1.5 mAh Li Ions with 46-to-81% efficiency.