This paper presents the concept and measurements of a new microwave rectifier based on the time reversal duality of power amplifiers. It is shown that the proposed rectifier can simultaneously provide high efficiency at large input power range over much more improved bandwidth compared to the conventional rectifier from time reversal duality. It is also reported that the proposed rectifier allows reconfiguration of the efficiency at input power range without placing the tunable elements. A 10 W wideband power amplifier with 79%drain efficiency at 1.85 GHz is used to validate the concept. By making the gate bias network short-terminated and replacing the drain termination with the DC load resistor for power amplifier, the circuit can operate as microwave rectifier with taking part of bandwidth from power amplifier. Measurements show the efficiency bandwidth with larger than 70 % rectifying efficiency at 15 dB input power range over a 1.7–1.95 GHz frequency range. The measurements thereby validate the presented concept and demonstrate the potential of the proposed rectifier for use in future wireless energy harvesting applications.

In this paper, the design of a 10 mW concurrent triband RF rectifier at 1050 , 2050 and 2600 MHz using the high impedance transmission line with two short stubs is presented. Experimental results show that the efficiency is achieved 59.2 % at 1050 MHz, 35.6 % at 2050 MHz and 52.2 % at 2600 MHz. Compared to the state-of-the-art of multi-band rectifiers, the proposed triband rectifier has the ability to harvest RF energy from the corresponding operating frequencies sources.

This paper proposes a filter realised using only lumped-element components, implemented as a highly selective bandpass filter suitable for lowpass delta-sigma (LPΔΣ) RF transmitters. The proposed filter is characterised by low insertion loss, high selectivity and a transfer function tailored for filtering the close-up out-of-band noise of LPΔΣ RF transmitters. The circuit design is based on a modified loaded-stub ring-resonator structure, however, implemented using 4 π-shape lumped-element resonators with LC tanks. The measurements show good agreement with simulation and the proposed filter provides a fractional 3-dB bandwidth of 14.3 %, insertion loss of less than 1.6 dB, suppression of more than 18 dB on both sides of the desired band, and a sharp cut-off frequency response. This filter is combined with the delta-sigma transmitter to show the effective reduction of the out-of-band quantisation noise signals.

This paper proposes a novel implementation of a high frequency rectifier, which is realised using the simplified real frequency technique. The optimum impedances presented at the diode package plane are found from source-pull simulation over a broad frequency range. The implemented broadband rectifiers show good performance in terms of efficiency and bandwidth. Using a HSMS 2820 Schottky diode device, greater than 50 % efficiency has been measured from 1.25 GHz to 2.25 GHz. Furthermore, greater than 60 % efficiency with 14 dB (from 12 dBm to 26 dBm) input power dynamic range is achieved at 1.8 GHz. Peak efficiency of 77 % is obtained at the input power of 23 dBm. The high efficiency over such a large bandwidth is believed to be the best reported to data in open literature at these frequencies.

This paper proposes a novel configuration of the rectifier which is realised using a high impedance inductor. It removes the input matching network concerning the trade-off of the efficiency and bandwidth. The rectifier with better than 40 % efficiency is designed and measured across the frequency band from 40 MHz to 4740 MHz. The peak RF-DC conversion efficiency of 60.3 % is achieved at 1 GHz operating frequency with 23 dBm incident power. In addition, a minimum of 2 V output DC voltage and greater than 40 % efficiency with 5 dB input power dynamic range from 20 dBm to 25 dBm is obtained covering the entire band.

This paper proposes a highly selective bandpass filter suitable for lowpass delta-sigma RF transmitters. The proposed filter is characterized by a low insertion loss, high selectivity and a transfer function tailored for filtering the close-up out-of-band noise of lowpass delta-sigma transmitters. The circuit design is based on a modified stub-loaded ring resonator structure. The proposed filter has been implemented and the measurements show good agreement with simulation. The proposed filter provides a fractional 3-dB bandwidth of 14.6 %, an insertion loss of less than 1.3 dB, a suppression of more than 15 dB on both sides of desired band, and a sharp cut-off frequency response.

This paper presents a dual-band rectifying circuit for wireless power transmission working at 2.45 GHz and 5.8 GHz. A modified dual-band matching network is adopted to realize the highly efficient dual-band rectifier. Source-pull simulations are performed, to determine the proper impedances at the two different frequencies. The proposed dual-band rectifier has been implemented and the measurements show good agreement with simulation. With a dual-band input matching network, the measurement results for an input power level of 10 mW show peak RF-to-DC efficiencies of 66.8 % and 51.5 % at 2.45 GHz and 5.8 GHz respectively.

This paper proposes an energy recovery rectifier suitable for the use in outphasing and/or linear amplification with nonlinear components (LINC) transmitters. The proposed application oriented rectifier consists of a high-efficiency resistive rectifier and a stepped-impedance resonator (SIR) which stores the energy in order to reduce load sensitivity of the circuit. The rectifier is designed including harmonic frequency control to improve conversion efficiency and to provide a resistive input impedance at the fundamental frequency. The proposed rectifier has been implemented in hybrid technology. The fabricated circuit provides peak RF-to-DC efficiency of 73.5 % at 2.3 GHz and more than 60 % over a dynamic range of 8 dB. Furthermore, measurements show good agreement with simulation results.

This paper presents a high-efficiency rectifying circuit for wireless power transmission at 2.45 GHz. A filtering and matching network designed by quarter wavelength stubs was developed for suppressing the second and the third order harmonics of 2.45 GHz, 4.9 GHz and 7.35 GHz, respectively. The measured RF-to-DC conversion efficiency is 66.5 % for an input power level of 10 mW.

Using coplanar waveguide (CPW) to construct left-handed(LH) transmission line is more effective method than microstrip line. In this paper, a new type of LH transmission-line is proposed. It is composed with parallel embedded inductive and serial interdigital capacitor. Through extracting ß parameter of CPW transmission line, the region of LH transmission-line is obtained from 6 GHz to 14 GHz. The effective bandwidth is about 52% in 7.5 GHz-12.7 GHz. The backward-wave characteristic is validated by full-wave simulation.