An integrated RF-powered Li-ion battery charger solution has been developed for biomedical applications. RF energy received through an antenna is rectified, regulated, and passed on to a battery charger circuit that charges a Li-ion battery efficiently and accurately. The charger system has been implemented using UMC 90nm BiCMOS process library. Experimental results show that a battery model with internal resistance of 300mΩ and internal capacitance of 10mF can be charged to its full capacity at 3.5V in 0.2ms by a 2mW 10MHz RF power source referred from the antenna. The implemented charger circuit consumes only 240 uW.