High-Efficiency Transmission for Medical Implants

Medical implants require an internal supply voltage able to deliver a certain quantity of power. This power has to be transmitted by a pair of weakly coupled coils. In order to do this, the dc voltage of the external battery has to be converted into an ac signal. Inside the body, this ac signal has to be converted again into a dc voltage. The efficiency that can be obtained depends on the coupling factor, the quality factor of the coils, the driver circuit, and the regulator circuit.