An RF-to-DC Rectifier With High Efficiency Over Wide Input Power Range for RF Energy Harvesting Applications

This paper presents, a wide input range, 4-stage threshold voltage compensated RF-to-DC power converter, designed to efficiently convert RF signals to dc voltages by applying an optimum compensation voltage produced by subthreshold auxiliary transistors. The proposed optimally compensated rectifiers can achieve higher efficiency over a wider input power range compared to other threshold voltage compensation circuits where the level of the compensation is limited by the circuit structure and varies with input power. The designed rectifier is implemented in three possible ways. This proposed compensation technique can be applied to a rectifier chain with a relatively low number of stages. Designed and implemented in a 130 nm CMOS technology, the proposed rectifier exhibits a measured PCE of above 20 over the 8.5-dB input power range while driving a 1- $\text{M}\Omega $ load resistor at 896-MHz. For the same load and utilizing a minimal number of compensated rectifier stages, the proposed circuit exhibits a maximum PCE of 43 at -11 dBm for single-ended Dickson-based CMOS rectifiers. The proposed circuit demonstrates a -20.5 dBm sensitivity for 1 V output across a 1- $\text{M}\Omega $ resistive load.