Low-Power RF Energy Harvester Circuit Design for Wearable Medical Applications

Electromagnetic based energy harvesting systems are being widely researched with radio frequency (RF) as their energy source. RF energy is preferred due to its availability and characteristics of transferring energy remotely and in all directions. This paper presents a newly design low-power CMOS full-bridge rectifier which works as the receiver of the harvesting system. The proposed rectifier scheme includes two NMOS and two PMOS devices and they are realized in a standard 130nm CMOS process. The work is focused on RF signals of around 900 MHz. To achieve stable energy transmission between the antenna and the proposed AC-DC rectifier, an impedance matching network is designed with values of capacitor and inductor of 550fF and 45nH, respectively. A DC-DC converter with a Maximum Power Point Tracking (MPPT) system is designed for storing energy from the RF signal with minimum current consumption. The peak efficiency of this design is about 5% at 10 dBm. The overall system is very light-weight and requires no external wiring and connection.