A Li-ion battery charging design for biomedical implants

A Li-ion battery charging design for wireless medical implants is presented. Not only the power density is limited in the medical implants, but also the inherent lack of efficiency in a wireless powered system restricts the stability of power supply for medical implants. Therefore, a simple and power saving circuit is proposed to charge the Li-ion battery with 0.1 C. In order to resist the ripple of the voltage supplied of the carrier wave from the inducing coil, a special bias circuit to generate a bias voltage which varies with supply voltage has been designed. Moreover, the proposed design with a protection circuit can limit over-charge voltage of the Li-ion battery to prevent any damage.