A Novel and Compact Design of High-Efficiency Broadband Rectifier for Energy Harvesting and Wireless Power Transfer

In this paper, a novel and compact structure is presented for designing a rectifier with broad operating bandwidth and high efficiency for energy harvesting and wireless power transfer based on shunt-diode configuration. Specifically, different from the conventional structure of shunt-diode configuration, the proposed structure employs a combination of two diodes and only two transmission lines that lead to a very compact size. The proposed rectifier can be matched to the source impedance when two diode branches have conjugate impedances. The admittances of two branches are analyzed based on the theory that leads to the parameters of two transmission lines can be derived by closed-forms equations. For validation, a broadband rectifier based on Schottky diode BAT15–03W was designed, simulated, fabricated, and measured showing that the rectifier can operate in the fractional bandwidth of 63.9% from 1.64 GHz to 3.18 GHZ with the condition of higher 70% power conversion efficiency or fractional bandwidth of 99.1% from 1.34 GHz to 3.97 GHz with the condition of over 50% power conversion efficiency at 13 dBm input power. Moreover, the size of the rectifier is very compact, it is recorded as only 15 mm
$\times14$
mm. In comparison with the published broadband rectifiers, the proposed rectifier has many advantages such as smaller size and wider bandwidth.