Nonlinear Modeling and Harmonic Recycling of Millimeter-Wave Rectifier Circuit

This paper presents and demonstrates a harmonic harvesting technique, which aims at rerectifying and recycling the rectifier output harmonics in order to increase the RF-to-dc conversion efficiency. Firstly, an analytical framework is developed based on the Ritz-Galerkin technique to investigate the output power distribution of a simple millimeter-wave rectifier circuit over its dc and generated harmonics components. The numerical results show that about 32% and 66% of the output power is distributed over the dc component and the first harmonic, respectively. In order to recycle and harvest the first harmonic power component, a 35-GHz voltage doubler rectifier implemented in microstrip technology and capable of harmonic harvesting is then studied and designed. To evaluate the performance of the proposed rectifier, the conventional voltage doubler and the harmonic signal rectifiers are fabricated and measured. The measured RF-to-dc conversion efficiencies of 34% at 20-mW input RF power for the harmonic harvester configuration, and 23% at the same input RF power level for the conventional voltage doubler are observed. Moreover, it is shown that the proposed harmonic rectifier suggests about 12% efficiency improvement compared to previously reported millimeter-wave rectifiers at the same level of input power (20 mW). The proposed rectifier configuration can find potential applications in the development of millimeter-wave wireless power transmission devices operating at medium power range (1-100 mW).