Wireless charging technology using magnetically coupled resonators

We are successful to charge the iPod touch using magnetically coupled resonators. The wireless charging was possible within the distance variation within 10 cm. The signal was generated and amplified with the balanced power amplifier structure which is useful for isolating the reflected power near the operation frequency of 9.4 MHz. To reduce the size of the receiving part, we implanted the thin coil on the polycarbonate substrate using ultrasonic. The receiving circuits are made of rectifying circuit using Schottky diode and over voltage protection circuit.