A 2.7-kW, 29-MHz class-E/F/sub odd/ amplifier with a distributed active transformer

A Class-E/Fodd high power amplifier (PA) using the distributed active transformer (DAT) is demonstrated at 29MHz. The DAT combines the output power from four VDMOS push-pull pairs. The zero voltage switching (ZVS) condition is investigated and modified for the Class-E/Fodd amplifier with a non-ideal output transformer. All lumped elements including the DAT and the transistor package are modeled and optimized to achieve the ZVS condition and the high drain efficiency. The PA exhibits 2.7kW output power with 79% drain efficiency and 18dB gain at 29MHz

The Class-E/F Family of ZVS Switching Amplifiers

A new family of switching amplifiers, each member having some of the features of both class E and inverse F, is introduced. These class-E/F amplifiers have class-E features such as incorporation of the transistor parasitic capacitance into the circuit, exact truly switching time-domain solutions, and allowance for zero-voltage-switching operation. Additionally, some number of harmonics may be tuned in the fashion of inverse class F in order to achieve more desirable voltage and current waveforms for improved performance. Operational waveforms for several implementations are presented, and efficiency estimates are compared to class-E

Efficient, High power Precision RF and mmWave Digital Transmitter Architectures

Digital transmitters offer several advantages over conventional analog transmitters such as reconfigurability, elimination of scaling-unfriendly, power hungry and bulky analog blocks and portability across technology. The rapid advancement of technology in CMOS processes also enables integration of complex digital signal processing circuitry on the same die as the digital transmitter to compensate for their non-idealities. The use of this digital assistance can, for instance, enable the use of highly efficient but nonlinear switching-class power amplifiers by compensating for their severe nonlinearity through digital predistortion. While this shift to digitally intensive transmitter architectures is propelled by the benefits stated above, several pressing challenges arise that vary in their nature depending on the frequency of operation - from RF to mmWave. Millimeter wave CMOS power amplifiers have traditionally been limited in output power due to the low breakdown voltage of scaled CMOS technologies and poor quality of on-chip passives. Moreover, high data-rates and efficient spectrum utilization demand highly linear power amplifiers with high efficiency under back-off. However, linearity and high efficiency are traditionally at odds with each other in conventional power amplifier design. In this dissertation, digital assistance is used to relax this trade-off and enable the use of state-of-the-art switching class power amplifiers. A novel digital transmitter architecture which simultaneously employs aggressive device-stacking and large-scale power combining for watt-class output power, dynamic load modulation for linearization, and improved efficiency under back-off by supply-switching and load modulation is presented. At RF frequencies, while the problem of watt-class power amplification has been long solved, more pressing challenges arise from the crowded spectrum in this regime. A major drawback of digital transmitters is the absence of a reconstruction filter after digital-to-analog conversion which causes the baseband quantization noise to get upconverted to RF and amplified at the output of the transmitter. In high power transmitters, this upconverted noise can be so strong as to prevent their use in FDD systems due to receiver desensitization or impose stringent coexistence challenges. In this dissertation, new quantization noise suppression techniques are presented which, for the first time, contribute toward making watt-class fully-integrated digital RF transmitters a viable alternative for FDD and coexistence scenarios. Specifically, the techniques involve embedding a mixed-domain multi-tap FIR filter within highly-efficient watt-class switching power amplifiers to suppress quantization noise, enhancing the bandwidth of noise suppression, enabling tunable location of suppression and overcoming the limitations of purely digital-domain filtering techniques for quantization noise

Power Amplifiers for Next Generation Wireless Platforms

Class-E amplifier has the potential to deliver high efficiency required for the next generation wireless systems. In this journal, we discuss a novel load pull analysis technique to characterize the efficiency performance of Class-E amplifier in an outphasing power combining scheme. Class-E amplifier is not an ideal current or voltage source as is required for the traditional analysis of outphasing structures. It requires a phase modulated input signal and has a non-linear transfer characteristic which is a function of load impedance. Here we define an operating load locus based on the load pull analysis which can be used to predict the non-linear transfer function, efficiency, output power, input drive phase and many other factors associated with the outphasing class-E amplifier. This scheme could also be used to characterize any amplifier class in an outphasing structure. Finally modulation performance of Class-E amplifier using PWM technique is also presented

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

Class E/F switching power amplifiers

The present invention discloses a new family of switching amplifier classes called class E/F amplifiers. These amplifiers are generally characterized by their use of the zero-voltage-switching (ZVS) phase correction technique to eliminate of the loss normally associated with the inherent capacitance of the switching device as utilized in class-E amplifiers, together with a load network for improved voltage and current wave-shaping by presenting class-F.sup.-1 impedances at selected overtones and class-E impedances at the remaining overtones. The present invention discloses a several topologies and specific circuit implementations for achieving such performance

Microwave class-E power amplifiers

This paper reviews circuit architectures and demonstrated class-E power amplifiers in the UHF and microwave frequency range. Scaling class-E soft-switching operation to high frequencies presents a number of challenges, particularly in the control of parasitic reactances of the device and the circuit. Different approaches have been taken, from using parasitics of lumped elements to provide the correct fundamental and harmonic impedances in the UHF range, to transmission-line implementations at frequencies above 10GHz

Microwave class-E power amplifiers: a brief review of essential concepts in high-frequency class-E PAs and related circuits

Since Nathan Sokal's invention of the class-E power amplifier (PA), the vast majority of class-E results have been reported at kilohertz and millihertz frequencies, but the concept is increasingly applied in the ultrahigh-frequency (UHF) [1]-[13], microwave [14]-[20], and even millimeter-wave range [21]. The goal of this article is to briefly review some interesting concepts concerning high-frequency class-E PAs and related circuits. (The article on page 26 of this issue, "A History of Switching-Mode Class-E Techniques" by Andrei Grebennikov and Frederick H. Raab, provides a historical overview of class-E amplifier development.)We acknowledge support, in part, by a Lockheed Martin Endowed Chair at the University of Colorado and in part by the Spanish Ministry of Economy, Industry, and Competitiveness (MINECO) through TEC2014-58341-C4-1-R and TEC2017-83343-C4-1-R projects, cofunded with FEDER

Optimization Of 5.7 Ghz Class E Power Amplifier For The Application Of Envelope Elimination And Restoration

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2007Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2007Rekabetin yoğun olduğu günümüzde tasarımcılar hafif, boyutları daha küçük ve düşük güçle çalışan yüksek performanslı ürün geliştirmenin yollarını aramaktadırlar. RF alıcı uygulamalarında güç kuvvetlendiricileri en fazla güç sarfiyatının olduğu bölümdür. Kablosuz iletişim sistemlerinde güç küvvetlendiricisi verimi maliyeti direkt olarak etkilemektedir. Teorik olarak %100 verim elde edilebilen E-sınıfı güç kuvvetlendiricileri transistorların açık/kapalı durum geçişlerinde güç sarfiyatını minimize edebilmektedir. Ayrıca çıkış gerilimi kaynak gerilimi ile doğrusal değişmektedir. Bu çalışmada E sınıfı güç kuvvetlendiricilerinin tasarım metodları ele alınmıştır. 5.7 GHz de çalışan birinde toplu devre elemanları, diğerinde transmisyon hattı elemanları kullanımış E sınıfı güç kuvvetlendiricileri tasarlanmıştır. Her iki devrede de %50 güç ekli verim (GEV) ve 500mW çıkış gücü elde edilmiştir. Sinyaldeki bozulmayı azaltmak için başvurulan doğrusallaştırma yöntemi Zarf Yoketme ve Tekrar Oluşturma metodudur. E sınıfı kuvvetlendiricinin Zarf Yoketme ve Tekrar Oluşturma yöntemi kullanılarak doğrusallaştırılmasıyla IMD bileşenlerinde 7.5 dB azalmış olup seviyesi gerçek işaretin 20dB altındadır.In today’s competitive, manufactures and product developers are seeking ways to build high performance devices that are lighter in weight, smaller in size and operating at lower power. In transceiver applications one module is responsible for a large portion of the power consumption - the power amplifier. The efficiency of the power amplifier has a direct impact on the cost of the wireless communication system. The class-E amplifier has a maximum theoretical efficiency of 100%. Class E power amplifiers have the ability to minimize power loss during on/off transitions of the transistor. Also, the output voltage varies linearly with the supply voltage. This thesis describes the design and the linearization methodology of the Class E amplifiers. Two class-E amplifiers operating at 5.7 GHz are presented. One of them is a lumped elements based circuit and the other is a transmission lines based circuit. Both circuit show good performance with 50% PAE and have 500mW output power. Envelope elimination and restoration is the linearization method chosen to achieve reduction of signal distortion. Linearization Class E PA using EER system provides an additional 7.5 dB reduction in intermodulation distortion products, achieving a minimum distortion level of 20 dB below the fundamental signals.Yüksek LisansM.Sc

Optimization of 8-Plate Multi-Resonant Coupling Structure Using Class-E\u3csup\u3e2\u3c/sup\u3e Based Capacitive-Wireless Power Transfer System

Capacitive-wireless power transfer (CPT) effectively charges battery-powered devices without a physical contact. It is an alternative to inductive-wireless power transfer (IPT) which is available in the present market. Compared with IPT, CPT offers flexibility in designing the coupling section. Because of its flexibility, CPT utilizes various coupling methods to enhance the coupling capacitance. Misalignment is a common issue in any WPT system. Among IPT and CPT, IPT has better performance for misalignments, but it requires bulk and expensive ferrite core to attain a high coupling coefficient. This work focuses on designing a CPT system to minimize the impact of misalignments. In this research, a novel 8-plate multi-resonant Class-E2 CPT system is developed to improve the performance of the CPT system for misalignments. The proposed CPT model expands the resonant frequency band, which results in better performance for misalignments compared with the regular 4-plate CPT system. The 8-plate coupling structure is designed to charge a 100 Ah drone battery. For this application, the coupling is formed when the drone lands on the capacitive- wireless charging pad. This work also presents the analysis of several dielectric materials with different dielectric constants. A well-designed capacitive coupler can effectively limit harmonics during the interaction between transmitter and receiver. Also, the effect of coupling plate shape is identified on the CPT system. The hardware tests indicate the round-shaped plates have better stability in coupling capacitance with the variation in frequency. The effect of misalignments is studied through the impedance tracking of the Class-E2 power converter. Impedance plots for 50 μH, and 100 μH resonant inductors are used to determine input current peak for each case. Additionally, hardware tests are performed to study the variation of input current and output voltage for a range of frequencies. The test results indicate the efficiency at optimal impedance point for a resonant inductor with 50 μH is 8% higher compared to the CPT with a 100 μH resonant inductor which highlights the effects of the resonant inductor on efficiency. The zero-voltage-switching (ZVS) limits are also identified for varying frequencies and duty cycles. Later in this research, the optimal design of the Class-E rectifier is identified to enhance the power transfer. Several cases were considered to investigate the impact of the secondary inductor on the output voltage and the ZVS property. Hardware tests validate that under optimal conditions the efficiency of the Class-E2 based CPT system improves by 18% compared with Ar \u3e\u3c 1. Further work presents the advantages of 8-plate multi-resonant coupling for misalignments. The proposed model has a simple design procedure which enhances the power flow from the inverter to the rectifier section. The hardware results of the proposed 8-plate multi-resonant coupling show an increase in efficiency to 88.5% for the 20.8 W test, which is 18% higher than regular 4-plate coupling. Because of the wider resonant frequency band [455- 485 kHz], compared with regular 4-plate coupling, the proposed design minimized the output voltage drop by 15% for 10% misalignment. Even for large misalignments, 8-plate improves the CPT performance by 40% compared with 4-plate coupling