Book•
RF Power Amplifiers for Wireless Communications
31 Mar 1999-
TL;DR: In this paper, the authors present a power amplifier design for GHz frequency bands at GHz GHz frequency band with overdrive and overdrive-only overdrive modes, as well as a switch-mode Amplifier for RF applications.
Abstract: Linear PA Design. Conventional High-Efficiency Amplifier Modes. Class AB PAs at GHz Frequencies. Practical Design of Class AB PAs. Overdrive and the Class F Mode. Switching Mode Amplifiers for RF Applications. Switching PA Modes at GHz Frequencies. Signals, Modulation Systems, and PA Nonlinearities. Efficiency Enhancement Techniques. Power Amplifier Bias Circuit Design. Power Amplifier Architecture. PA Linearization Techniques.
Citations
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TL;DR: The most important addenda of the proposed E3F are a sophisticated power model for various base station types, as well as large-scale long-term traffic models, which are applied to quantify the energy efficiency of the downlink of a 3GPP LTE radio access network.
Abstract: In order to quantify the energy efficiency of a wireless network, the power consumption of the entire system needs to be captured. In this article, the necessary extensions with respect to existing performance evaluation frameworks are discussed. The most important addenda of the proposed energy efficiency evaluation framework (E3F) are a sophisticated power model for various base station types, as well as large-scale long-term traffic models. The BS power model maps the RF output power radiated at the antenna elements to the total supply power of a BS site. The proposed traffic model emulates the spatial distribution of the traffic demands over large geographical regions, including urban and rural areas, as well as temporal variations between peak and off-peak hours. Finally, the E3F is applied to quantify the energy efficiency of the downlink of a 3GPP LTE radio access network.
1,462 citations
TL;DR: In this article, a wide variety of techniques, implementations, and active devices are presented to generate RF/microwave power for wireless communications, but also in applications such as jamming, imaging, RF heating, and miniature dc/dc converters.
Abstract: The generation of RF/microwave power is required not only in wireless communications, but also in applications such as jamming, imaging, RF heating, and miniature dc/dc converters. Each application has its own unique requirements for frequency, bandwidth, load, power, efficiency, linearity, and cost. RF power is generated by a wide variety of techniques, implementations, and active devices. Power amplifiers are incorporated into transmitters in a similarly wide variety of architectures, including linear, Kalm, envelope tracking, outphasing, and Doherty. Linearity can be improved through techniques such as feedback, feedforward, and predistortion.
1,335 citations
TL;DR: A memory polynomial model for the predistorter is proposed and implemented using an indirect learning architecture and linearization performance is demonstrated on a three-carrier WCDMA signal.
Abstract: Power amplifiers (PAs) are inherently nonlinear devices and are used in virtually all communications systems. Digital baseband predistortion is a highly cost-effective way to linearize PAs, but most existing architectures assume that the PA has a memoryless nonlinearity. For wider bandwidth applications such as wideband code-division multiple access (WCDMA) or wideband orthogonal frequency-division multiplexing (W-OFDM), PA memory effects can no longer be ignored, and memoryless predistortion has limited effectiveness. In this paper, instead of focusing on a particular PA model and building a corresponding predistorter, we focus directly on the predistorter structure. In particular, we propose a memory polynomial model for the predistorter and implement it using an indirect learning architecture. Linearization performance is demonstrated on a three-carrier WCDMA signal.
1,160 citations
Cites background from "RF Power Amplifiers for Wireless Co..."
...on memoryless predistortion during the past decade [1]....
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TL;DR: Examples of broadband amplifiers, as well as several of the main areas of high-efficiency amplifier design-notably Class-D, Class-E, class-F, and Class-J approaches, Doherty PAs, envelope-tracking techniques, and Chireix outphasing are described.
Abstract: Gallium-nitride power transistor (GaN HEMT) and integrated circuit technologies have matured dramatically over the last few years, and many hundreds of thousands of devices have been manufactured and fielded in applications ranging from pulsed radars and counter-IED jammers to CATV modules and fourth-generation infrastructure base-stations. GaN HEMT devices, exhibiting high power densities coupled with high breakdown voltages, have opened up the possibilities for highly efficient power amplifiers (PAs) exploiting the principles of waveform engineered designs. This paper summarizes the unique advantages of GaN HEMTs compared to other power transistor technologies, with examples of where such features have been exploited. Since RF power densities of GaN HEMTs are many times higher than other technologies, much attention has also been given to thermal management-examples of both commercial “off-the-shelf” packaging as well as custom heat-sinks are described. The very desirable feature of having accurate large-signal models for both discrete transistors and monolithic microwave integrated circuit foundry are emphasized with a number of circuit design examples. GaN HEMT technology has been a major enabler for both very broadband high-PAs and very high-efficiency designs. This paper describes examples of broadband amplifiers, as well as several of the main areas of high-efficiency amplifier design-notably Class-D, Class-E, Class-F, and Class-J approaches, Doherty PAs, envelope-tracking techniques, and Chireix outphasing.
840 citations
Cites background from "RF Power Amplifiers for Wireless Co..."
...In general, there has been a lot of attention given to “waveform engineering” in the last few years [37], [38]—this has undoubtedly been due to the fact that GaN HEMT devices allow voltage and current swings on the drains of the devices that can far exceed other RF power semiconductor technologies....
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Book•
31 Jan 2003
TL;DR: This book discusses Solid-State Device Modeling, Volterra-Series and Power-Series Analysis, and Harmonic-Balance analysis of Balanced Circuits and Active Mixers.
Abstract: Preface. Introduction, Fundamental Concepts, and Definitions. Solid-State Device Modeling. Harmonic-Balance analysis. Volterra-Series and Power-Series Analysis. Balanced Circuits. Diode Mixers. Diode Frequency Multipliers. Small-Signal Amplifiers. Power Amplifiers. Active Frequency Multipliers. Active Mixers. Oscillators. Index.
662 citations
References
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TL;DR: In this paper, the basic relationship among the Fourier coefficients of the waveforms and the performance of the amplifier was derived for maximally flat waveforms, and the Amplifier performance was tabulated as a function of which harmonics are included in the voltage and current waveforms.
Abstract: Class-F power amplifiers (PA's) employ harmonic-frequency resonators to shape their drain or collector waveforms to improve efficiency. Generally, the output network must present the drain with either an open or short circuit at the harmonic frequencies. At VHF and higher frequencies, the drain capacitance, lead inductance, lead length, and dispersion make implementation of reasonably ideal tuned circuits difficult. However it is possible to control the impedances at a finite number of harmonics. This note first derives the basic relationships among the Fourier coefficients of the waveforms and the performance of the amplifier. Fourier coefficients for maximally flat waveforms are then derived for inclusion of up to the fifth harmonic. Amplifier performance is then tabulated as a function of which harmonics are included in the voltage and current waveforms. Efficiency increases from 50% of class A toward 100% as harmonics are added. Power-output capability increases by up to 27%.
500 citations
"RF Power Amplifiers for Wireless Co..." refers background in this paper
...“Quirky” is an appropriate term for varactors, given that a simple L-C-R series combination, which incorporates a varactor as the capacitive element, can display chaotic behavior under some conditions [3]....
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...The basic results of matched two-port linear RF amplifiers were derived originally by Mason [1] and Rollett [2], although most microwave engineers first encounter these results in a famous application note (“AN-95”) written by Bodway under the old Hewlett Packard label and still available from Agilent [3]....
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...It is even possible that the nonlinear C-V characteristic of the input junction could be harnessed to do some beneficial wave shaping [3]; this will be considered further in Chapter 4....
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...1 1.2 Linear RF Amplifier Theory The basic results of matched two-port linear RF amplifiers were derived originally by Mason [1] and Rollett [2], although most microwave engineers first encounter these results in a famous application note (“AN-95”) written by Bodway under the old Hewlett Packard label and still available from Agilent [3]....
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...There has been much published analysis on this class of transmission line [3], but their applications have been largely limited to very specialized applications, such as fast pulse transmission....
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01 May 1989
TL;DR: In this paper, a prototype direct conversion transceiver for portable mobile radio terminals has been developed and is under evaluation and test results are presented showing the performance of this transceiver to be equivalent to (and in some cases better than) that of existing systems.
Abstract: A prototype direct conversion transceiver for portable mobile radio terminals has been developed and is under evaluation. Test results are presented showing the performance of this transceiver to be equivalent to (and in some cases better than) that of existing systems. The transmitter and receiver are described, and the receiver fading performance is examined. The results presented show that a direct conversion transceiver system can be made to work at both VHF and UHF. The improved channel characteristics facilitated by digital channel filtering make this configuration particularly suited to data transmission. In addition, the integration potential of all the system components is important for the concept of a 'personal communicator'. >
93 citations
Patent•
08 Mar 2001
TL;DR: In this article, the authors proposed a method for improving the efficiency and the dynamic range of a power amplifier operated with signals having a large peak-to-average ratio (P2A) in terms of the magnitude of an input signal being a modulated signal that is input to the power amplifier.
Abstract: Method and apparatus for improving the efficiency and the dynamic range of a power amplifier operated with signals having a large peak-to-average ratio. A reference level is determined, above which at least a portion of the magnitude of an input signal being a modulated signal that is input to the power amplifier, or a baseband waveform that is used to generate the modulated signal, is defined as an excess input signal. The magnitude of the input signal is continuously sampled, for detecting an excess input signal. A lower level of operating voltage is supplied to the power amplifier, if no excess input signal is detected. The lower level of operating voltage is sufficient to effectively amplify input signals having a magnitude below the reference level. A higher level of operating voltage is supplied to the power amplifier, whenever an excess input signal is detected. The higher level of operating voltage is sufficient to effectively amplify input signals having a magnitude above the reference level.
89 citations
TL;DR: In this paper, a new approach to the design of s.s.b. transmitters is proposed based on the generation of r.f. energy at channel frequency and the use of a feedback control system to regulate the output spectrum of the transmitter.
Abstract: A new approach to the design of s.s.b. transmitters, which overcomes the problems of the present-day transmitters, is proposed. This is based on the generation of r.f. energy at channel frequency and the use of a feedback control system to regulate the output spectrum of the transmitter so that it approximates arbitrarily closely to that of a low-level s.s.b. signal generated in a conventional way. The principles of design are applicable to all frequencies and power levels, and also readily adaptable to other modes of modulation.
65 citations