A 433-MHz Compact Inverse Class-F Rectifier for Biomedical Wireless Power Transmission

This letter presents a novel implementation of inverse class-F (class-
$\text{F}^{-1}$
) rectifier based on lumped elements for biomedical wireless power transfer (WPT) at 433 MHz. Specifically, in order to reshape the diode current and voltage according to the class-
$\text{F}^{-1}$
waveform, a parallel LC resonator is deployed at the diode anode as a band-stop filter to provide infinite impedance for the second harmonic. Meanwhile, the third harmonic is terminated with zero impedance by a series LC network at the diode cathode side where its quality factor is also controlled to facilitate the fundamental matching. A prototype is fabricated and measured for verification showing that the peak power conversion efficiency (PCE) is achieved at 72.8% with an input power of 5 dBm. Also, the proposed rectifier exhibits
$\text {PCE}>50\% $
within a wide dynamic range of 22.5 dB and a compact size of
$13\times 7$
mm2, which indicates an advantageous performance over the other existing designs with similar diode and frequency.