High-Efficiency Harmonically Terminated Diode and Transistor Rectifiers

Abstract

Abstract-This paper presents a theoretical analysis of harmonically terminated high-efficiency power rectifiers and experimental validation on a class-C single Schottky-diode rectifier and a class-F GaN transistor rectifier. The theory is based on a Fourier analysis of current and voltage waveforms, which arise across the rectifying element when different harmonic terminations are presented at its terminals. An analogy to harmonically terminated power amplifier (PA) theory is discussed. From the analysis, one can obtain an optimal value for the dc load given the RF circuit design. An upper limit on rectifier efficiency is derived for each case as a function of the device on-resistance. Measured results from fundamental frequency source-pull measurement of a Schottky diode rectifier with short-circuit terminations at the second and third harmonics are presented. A maximal device rectification efficiency of 72.8% at 2.45 GHz matches the theoretical prediction. A 2.14-GHz GaN HEMT rectifier is designed based on a class-F PA. The gate of the transistor is terminated in an optimal impedance for self-synchronous rectification. Measurements of conversion efficiency and output dc voltage for varying gate RF impedance, dc load, and gate bias are shown with varying input RF power at the drain. The rectifier demonstrates an efficiency of 85% for a 10-W input RF power at the transistor drain with a dc voltage of 30 V across a 98-resistor.

Efficient transmitters and receivers for high-power wireless powering systems

“…High-efficiency harmonically terminated rectifiers with diodes and transistors at S-band frequencies were first discussed in [16]. A synchronous power rectifier at UHF frequencies was then demonstrated in [17], and a selfsynchronous rectifier with >80% efficiency was discussed in [18], where the 2.14GHz PA from the previous section was tested in rectifier mode.…”

“…The input power into the drain is of the same order as the output power when the device operates as a PA. The PA from [14] was tested as a rectifier and demonstrated an output power of 10W with 85% conversion efficiency when operated in self-synchronous mode into a 98-ohm DC load , as detailed in [16].…”

“…DISCUSSION AND CONCLUSIONS In conclusion, it is possible to operate a high-power highefficiency power amplifier as a high-efficiency power rectifier. This property can be theoretically derived under ideal assumptions using Fourier analysis as shown for class F -1 mode case in [16]. This is made possible by the fact that a rectifier and amplifier have inverse currents, sometimes referred to as "time-reversal".…”

“…In the UHF and microwave frequency range, diodes have power limitations, and power rectifiers are made either with distributed rectenna arrays or can be also implemented with transistors, e.g. [12].…”

High-efficiency X-Band MMIC GaN power amplifiers operating as rectifiers

“…Recently, advanced DC/DC converters have been demonstrated in the UHF frequency range with transistor rectifiers, scaled from low-frequency synchronous rectifier architectures [7], [8]. It has recently also been shown theoretically as well as experimentally at 2 GHz that a microwave transistor, when load impedances are well matched, can exhibit similar efficiency when operating either as a power amplifier or a rectifier, as a results of time-reversal duality [9], [10].…”