High-Efficiency Broadband Rectifier with Wide Ranges of Input Power and Output Load Based on Branch-Line Coupler

In this work, a novel rectifier based on a branch-line coupler is proposed to operate within wide ranges of input power, operating frequency and output load. In the proposed topology, two output ports of the coupler are connected with two identical sub-rectifiers and the isolation port is directly connected to the ground. The input impedance of the two sub-rectifiers varies with different input power, operating frequency and output load, which leads to impedance mismatching. By using the branch-line coupler with grounded isolation port, the power reflected from the two sub-rectifiers can be partially re-injected back to the sub-rectifiers. Thus, the power can be reused and the RF-dc conversion efficiency can be improved. Theoretical analysis and performance comparison are carried out. The results indicate that the proposed topology is able to realize high efficiency with wide input power, frequency and load dynamic ranges. For validation, a rectifier working at 2.45 GHz is designed. The fabricated rectifier circuit demonstrates a maximum RF-dc conversion efficiency of 80.8%. The measured efficiency remains over 70% with the input power from 10 dBm to 18.6 dBm and the operating frequency from 2.08 to 2.58 GHz.