This study introduces a novel single-diode rectenna, enhancing the rf-dc conversion efficiency using harmonic control of the antenna impedance. We employ source-pull simulations encompassing the fundamental frequency and the harmonics to achieve a highly efficient rectenna. The results of the source-pull simulations delineate the source-impedance ranges required for enhanced efficiency at each harmonic. Based on the source-pull simulation results, we designed two inverted-F antenna with input impedances within and without these identified source impedance ranges. Experimental results show that the proposed rectenna has a maximum rf-dc conversion efficiency of 75.9% at the fundamental frequency of 920 MHz, an input power of 10.8 dBm, and a load resistance of 1 kΩ, which is higher than that of the comparative rectenna without harmonic control of the antenna impedance. This study demonstrates that the proposed rectenna achieves high efficiency through the direct connection of the antenna and the single diode, along with harmonic control of the antenna impedance.

This paper presents a divide-by-9 injection-locked frequency divider (ILFD). It can lock onto about 6-GHz input with a locking range of 3.23GHz (58%). The basic concept of the ILFD is based on employing self-gated multiple inputs into the multiple-stage ring oscillator. A wide lock range is also realized by adapting harmonic-control circuits, which can boost specific harmonics generated by mixing. The ILFD was fabricated using a 55-nm deeply depleted channel (DDC) CMOS process. It occupies an area of 0.0210mm2, and consumes a power of 14.4mW.

A small-sized three-stage GaAs power module has been developed for portable digital radios using M-16QAM modulation. This module has exhibited typical P1dB of 10 W with PAE of 48% and a power gain of 35 dB at a low supply voltage of 6.5 V in 1.453-1.477 GHz band. The volume of the module is only 1.5 cc, which is one of the smallest value in 10 W class modules ever reported. In order to realize the reduced size and the high power performances simultaneously, the module has employed new power divider/combiner circuits with significant features of the reduced occupation area, the improved isolation properties and the function of second-harmonic control.