Light-Harvesting CMOS Power-Supply System for 0-10-mW Wireless Microsensors

摘要

Wireless microsensors in consumer products, homes, hospitals, and factories incorporate sensing, processing, and transmission intelligence that can save money, energy, and lives. Although their tiny batteries deplete quickly, harvesting light energy can replenish what they supply. Still, a 1-mm(2) photovoltaic (PV) cell can only generate up to 150 mu W of the milliwatts that a wireless micrasensor can consume. The battery-assisted light-powered harvester presented here therefore draws 10-130 mu W from a 1 x 1 mm(2) PV cell and assistance from a battery to supply a 10-mW load and recharge the battery with excess PV power. The CMOS system regulates its 1-V output within +/- 28 mV while supplying 10x more power per 1 mm(3) with 94.5% efficiency and 38x with 87.8% efficiency than the best light-harvesting microsystem reported. Unlike others whose efficiencies peak at one power level, efficiency here is 94.5% across v(PV) values 10-130 mu W and P-LD values 0.5-10 mW with an 18-mu H 3 x 3 x 1.5 mm(3) inductor and 87.8% with a 22-mu H 1.6 x 0.8 x 0.8 mm(3) device.