RF-powered Li-ion battery charger for biomedical applications

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 90 nm BiCMOS process library. Experimental results show that a battery model with internal resistance of 300 mOmega and internal capacitance of 10 mF can be charged to its full capacity at 3.5 V in 0.2 ms by a 2 mW 10 MHz RF power source referred from the antenna. The implemented charger circuit consumes only 240 uW.