A high-efficiency full-wave CMOS rectifying charge pump for RF energy harvesting applications

A high-efficiency integrated full-wave CMOS rectifying charge pump for radio-frequency (RF) energy harvesting was designed. By using the commercially available 40nm CMOS process, low-voltage operation as low as 0.4V was achieved by adopting body-connected PMOS diodes as the rectifying diodes and as switches for capacitor charging pump. A full-wave rectifying configuration was used to enhance the power conversion efficiency (PCE) of the converter. Simulation results indicate that the circuit can achieve a power efficiency of over 50.0% for an input voltage larger than 0.4V of a single narrow band 900MHz RF signal. Although the loading characteristics of the primitive charge pump, especially for 0.4V input which is just above the specific threshold voltage of the PMOS, is rather poor, and a large voltage drop due to the conduction loss was found when the load current increases, it may still be acceptable for battery charging applications. A regulation circuit based on the charge pump switching control was then proposed to improve the loading characteristics.