A noncontact power-supply card powered by solar cells for mobile communication

This paper describes a new noncontact power-supply card powered by solar cells. The card supplies 300 mW to an electronic device without having to come into contact with the device. The size is 86 mm × 54 mm × 3.7 mm. To make the card thinner, we developed a new 0.7-mm-thick coil that uses amorphous magnetic ribbon. A new rechargeable battery boosts the output power. The transmission power is three times larger than that of the previous model. Power management circuits are added to reduce energy consumption. A battery charging circuit that has an excellent temperature profile was developed. We investigated various receiving circuits. One of those circuits, which uses an electrical double-layer capacitor (EDLC) and a voltage regulator, is described.