An E-pHEMT self-biased and self-synchronous class E rectifier

In this paper, the design of a self-biased and self-synchronous class E rectifier, based on an Enhancement-mode Pseudomorphic High Electron Mobility Transistor (E-pHEMT), is proposed. Characterized by a small value of the switch-mode time-constant (the on-state resistance times the output capacitance), high power efficiency figures may be obtained when forcing zero-voltage and zero-voltage-derivative switching conditions (ZVS and ZVDS). The self-synchronous operation, made possible by the device gate-to-drain coupling capacitance, leads to a compact design, while the gate-to-source Schottky junction allows self-biasing the gate terminal in order to improve the efficiency versus input power profile. Simulations, based on an extracted simplified non-linear model, are combined with measured results for implementations at 900 MHz and 2.45 GHz. Efficiency values as high as 76% and 64% have been estimated at power levels of -4 dBm and -1 dBm, respectively, with peak figures of 88% and 77%.This work was supported by MINECO through projects TEC2011-29126-C03-01, co-funded with FEDER, and Consolider CSD2008-0006

Design of UHF class-E inverters and synchronous rectifiers for efficient transmission topologies

In this paper, the design of efficient transmitting architectures is addressed. Taking advantage of the modeling and characterization of novel active devices as GaN HEMT and E-pHEMT, several topologies have been approached. An outphasing transmitter at 770 MHz have been implemented from two class-E RFPA designed over package GaN HEMTs. In addition, for multiband applications, a dual band outphasing transmitter (able of operating either at 770 MHz or 960 MHz) has been also realized. A Chireix reactive combiner allows positioning the drain impedance loci to produce high efficiency and good dynamic range profiles, for both designs. Average drain efficiency figure over 61% has been measured for a 8.4 dB PAPR WCDMA signal, in the dual-band implementation. Besides, in the first approach, an efficient value of 57.5% was estimated when reproducing a LTE with a PAPR of 9.6 dB. On the other hand, wireless powering applications have been into account in the design of self-biased and self-synchronous class-E rectifier, based on an E-pHEMT. Two implementations at 900 MHz and 2.45 GHz, with efficient values of 76% and 64% at power levels of -4 dBm and -1 dBm, respectively, and peak figures of 88% and 77%, have been measured.This work was supported by MINECO through projects TEC2011-29126-C03-01, co-funded with FEDER, and Consolider CSD2008-00068

Device characterization and modeling for the design of UHF Class-E inverters and synchronous rectifiers

In this paper, the advantages derived from an appropriate characterization and modeling of active and passive devices, leading to the optimized design of Ultra-High Frequency (UHF) Class-E inverters and synchronous rectifiers, are highlighted. While the combination of a couple of low-frequency and RF measurement techniques is shown to be valid for the extraction of a simplified model as a switch, a more complex approach may be required if also addressing the design of the continuous wave (CW) driving network or if interested in taking fully advantage of other transistor characteristics. Design examples, based on GaN HEMTs and a GaAs E-pHEMT, are presented, in which the parasitics of the employed coils and capacitors are also taken into consideration. Wireless transmitting and powering applications have been addressed.This work was supported by the Spanish Ministry MINECO through projects TEC2011-29126-C03-01, co-funded with FEDER, and Consolider CSD2008-00068

Outphasing class-E/ F2 power amplifier using a quadrature hybrid as non-isolating combiner

This paper presents a GaN HEMT outphasing power amplifier (PA), based on a class-E/ F 2 topology with reduced sensitivity to variable resistive load operation, designed to provide output power control over an extended range with high efficiency. A 90-degree hybrid coupler is used as non-isolating combiner, incorporating an appropriate reactive termination on its fourth port. Besides its many intrinsic advantages, the mutual load modulation trajectories may be rotated by simply adjusting a capacitor value or alternatively the length of an open-circuited transmission line. Once implemented at UHF band, the outphasing PA provides a drain efficiency higher than 70% up to an output power 10 dB below its peak value (42.2 dBm).This work was supported by the Spanish Ministry of Science, Innovation and Universities through TEC2017-83343-C4-1-R project, co-funded with FEDER. D. Vegas also thanks for the BES-2015-072203 grant

Current-injected load-modulated outphasing amplifier for extended power range operation

In this letter, the power range to be covered with maximized efficiency by a two-way outphasing power amplifier (PA) is significantly extended thanks to a proposed architecture with injection of an external signal. Using a reactively terminated quadrature hybrid coupler (QHC) as non-isolating combiner, the Chireix topology is transformed into a slight variation of the Load-Modulated Balanced Amplifier (LMBA) when the auxiliary branch is activated. This combined LM strategy provides a nearly resistive loading of the individual outphasing PAs over a wide power range. An appropriate output network, approximating a class-E/F2 operation of the selected GaN HEMT device under such loading condition, leads to remarkable drain efficiency figures at deep output power back-off (OPBO). Values higher than 80%, 70% and 60% have been measured at power levels 9.5 dB, 13.3 dB and 15 dB below its peak (45.7 dBm), respectively. A 5 MHz LTE signal with a peak-to-average power ratio (PAPR) as high as 12.65 dB has been reproduced with an average efficiency above 62% and worst case adjacent channel leakage ratio (ACLR) of -31 dBc.This work was supported by the Spanish Ministry of Science, Innovation and Universities under Project TEC2017-83343-C4-1-R, cofunded by the European Fund for Economic and Regional Development (FEDER). The work of David Vegas was supported by the Spanish Ministry of Science, Innovation and Universities under Grant BES-2015-072203

A planar 75% efficient GaN 1.2-GHz DC-DC converter with self-synchronous rectifier

This paper presents the design and characterization of a DC-DC converter operating at 1.2GHz with a maximum efficiency of 75% at 4.6W output power, and with a maximum output power of 13W at 58% efficiency. The microwave converter consists of a GaN class-E power amplifier coupled to a GaN class-E rectifier. The circuit is planar and exhibits a power density of approximately 0.65W/cm3 at the 75% efficiency point. The rectifier can be operated with input gate drive or selfsynchronously with a single RF input.This work was funded by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000216 and by the Spanish Ministry of Economy and Competitiveness (MINECO) under the FEDER co-funded project TEC2011-29126-C03-01

Efficient class-E power amplifier for variable load operation

In this paper, a GaN HEMT class-E power amplifier (PA) has been designed for efficiently operating under variable load resistance at the 750 MHz frequency band. The desired zero voltage switching (ZVS) of the device can be approximated for a wide range of resistive loads, by means of a simple inductive impedance inverter, derived from [1]. The loadpull contours, obtained from simulations, allowed the drain terminating network to be properly adjusted in order to maximize the output power control while at the same time minimizing losses. Once the amplifier was implemented, an efficiency over 76% has been measured at 9.6 dB power back-off, with a peak of 85% at 50 Ω. In addition, the efficiency stays as high as 75% for a 150 MHz frequency range.This work has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through the TEC2014-58341-C4-1-R project with FEDER co-funding. David Vegas also thanks the support provided by the predoctoral grant BES-2015-072203

Rectificador síncrono clase E a E-pHEMT para aplicaciones de transmisión inalámbrica y reciclado de energía

In this paper, advantage is taken from the particular characteristics of Enhancement-mode Pseudomorphic High Electron Mobility Transistor (E-pHEMT) devices for the design of synchronous rectifiers with an unbiased gate. Based on one of them, the design of a class E synchronous rectifier working in the 900 MHz frequency band, is proposed. A lumped-element multi-harmonic class E amplifier was first designed, exploiting the time-reversal dualily, to then introduce a drain-to-gate feedback and operate it in the desired synchronous rectifying mode. Competitive efficiency figures are demonstrated over a significant input power, frequency and load resistance range. An efficiency peak of 83% has been measured at 17 dBm, staying above 70% for a 14 dB input power range, a distinguishing characteristic when compared to Schottky diode based alternatives. The verified AM-AM conversion linearity would also allow using the rectifier for the efficient extraction of a time-varying excitation envelope without significant distortion

GaN HEMT class-E rectifier for DC+AC power recovery

A 915 MHz GaN HEMT-based class-E rectifier is proposed in this paper to be used for DC+AC wireless power recovery. Taking advantage of the time reversal (TR) duality principle, the rectifier was derived from a class-E inverter, whose output network was designed for high-efficiency operation over a wide range of resistive loads. The addition of an appropriate gateside termination allows the device to be turned-on without an additional RF source for gate driving. The rectifier reduced sensitivity to load variation, as well as its capability for efficiently and linearly recovering the envelope of an AM RF excitation, were then characterized. An average efficiency of 82% has been measured for the combined RF-to-DC and RF-to-AC power conversion of a 1.6 W modulated carrier. Frequency multiplexing and frequency modulation alternatives for high-level DC+AC wireless power transmission are finally presented.This work was supported by the Ministry of Economy and Competitiveness (MINECO) through TEC2014-58341-C4-1-R and TEC2014-58341-C4-2-R projects, co-funded with FEDER. The authors wish to thank Prof. Christian Brañas, University of Cantabria, by his assistance with the transformer characterization. David Vegas and José R. Pérez-Cisneros also thank the support provided by the pre-doctoral BES-2015-072203 and the pre-doctoral mobility EEBB-I-15-10447 grants, respectively

UHF class E/F2 outphasing transmitter for 12 dB PAPR signals

This paper exploits the degree of freedom provided by the continuous class-E modes in order to reduce the impact of a FET on-state resistance when approximating the zero voltage switching (ZVS) operation along a wide range of resistive loads. A UHF class-E/F2 power amplifier (PA), which includes a lumped element drain terminating network to synthesize the optimal load modulation (LM) trajectory, has been designed to maintain an efficiency as high as possible along an output power control range above 10 dB. Based on this PA, an outphasing scheme in the 700 MHz frequency band has been implemented. It is shown to provide an efficiency higher than 60% up to an output power below 5% (-13 dB) of its peak value (47 W). Under mixed-mode operation and applying digital predistorsion (DPD), a 10 MHz LTE signal with a peak-to-average power ratio (PAPR) as high as 12.2 dB has been linearly reproduced with average efficiency and PAE values of 46.6% and 42.9%, respectively.This work was supported by Spanish Ministry of Science, Innovation and Universities through TEC2017-83343-C4-1-R project, co-funded with FEDER. D. Vegas also thanks for the BES-2015-072203 grant. The support provided by Prof. P. Gilabert and Prof. G. Montoro, UPC, on the GMP-LUT DPD is highly appreciated