A Fully Integrated LightPowering System with Integrated CMOS Photovoltaic Cell for Batteryless IoT Devices This paper presents a fully integrated CMOS lightpowering system, integrating CMOS photovoltaic cell and energy harvesting interface, for batteryless internet of things (IoT). The CMOS photovoltaic cell employs deep Nwell (DNW) based structure to improve the lightelectric conversion efficiency. The energy harvesting interface utilizes a fully integrated twostage switchedcapacitor dcdc converter to provide an appropriate output voltage for load circuits. It provides 1 V and 0.9xe2x80x931.1 V output under light load and heavy load, respectively. The chip is designed and fabricated by 180nm CMOS process, without using any offchip components, except a storage capacitor for testing. The experimental results demonstrate that the proposed 1mm x 2mm fully integrated lightpowering system can periodically provide 0.9 V to 1.1 V output voltage to power 1mA loading circuit. The proposed interface achieves 70 percent peakefficiency at  1 mumathrmA  and higher than 60 percent efficiency over  0.5 mumathrmA  to  2 mumathrmA  loading currents.

Highest Maximum Power Point of Radially Distant Inductively Coupled Power Receivers With Deep Submicron CMOS Inductively coupled power receivers for embedded microsensors are often tiny and distant from their transmitting sources. To sustain microsensors as long as possible, the power receiver should draw power whenever possible and output the highest power possible. Of reported stateoftheart technologies, switched resonant halfbridges require fewer components, are less breakdownlimited, and output as much or more power than the others. This paper derives and shows with measurements the highest possible maximum power point (MPP) for switched resonant halfbridges. The theory predicts the optimal time, duration, and frequency of the energy transfers that charge the battery. Measurements of a 0.18xcexbcm CMOS power receiver demonstrate that the receiver outputs more than 98.7% of the actual MPP at the predicted settings when the coupling factor between the transmitting and the receiving coils is 0.15%xe2x80x931.14%.