Optimization of RF- DC converter in micro energy harvester using voltage boosting network and bulk modulation technique for biomedical devices

This paper presents an optimization of the rectifier module for Radio Frequency (RF) energy harvesting system at 915 MHz band. This module converts the RF signal into direct-current voltage at the given frequency band to power ultra-low power bio-medical sensor. A transient analysis on various types of rectifier circuit is carried out to investigate their efficiency and sensitivity. To improve the power conversion efficiency, the voltage boosting network increases the voltage at the input of the full wave rectifier. By assuming the system is at resonance condition, the optimum parameters including the value of capacitance, inductance and load value are calculated. Simulation results show that passive component based circuit can significantly increase the RF input voltage and broaden the input range of the rectifier. The modified circuit enhances output voltage approximately 400 mV higher than output voltage from existing full wave rectifier at same level of input. This will help to increase the input range to be converted to dc output.