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.

Power amplifiers and transmitters for RF and microwave

A wide variety of semiconductor devices are used in wireless power amplifiers. The RF performance and other attributes of cellphone RF power amplifiers using Si and GaAs based technologies are reviewed and compared.

RF power amplifiers for wireless communications

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.

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A Review of GaN on SiC High Electron-Mobility Power Transistors and MMICs

This survey deals with 1/f noise in homogeneous semiconductor samples. A distinction is made between mobility noise and number noise. It is shown that there always is mobility noise with an /spl alpha/ value with a magnitude in the order of 10/sup -4/. Damaging the crystal has a strong influence on /spl alpha/, /spl alpha/ may increase by orders of magnitude. Some theoretical models are briefly discussed none of them can explain all experimental results. The /spl alpha/ values of several semiconductors are given. These values can be used in calculations of 1/f noise in devices. >

1/f Noise Sources

Energy-efficiency, one of the major design goals in wireless cellular networks, has received much attention lately, due to increased awareness of environmental and economic issues for network operators. In this paper, we develop a theoretical framework for BS energy saving that encompasses dynamic BS operation and the related problem of user association together. Specifically, we formulate a total cost minimization that allows for a flexible tradeoff between flow-level performance and energy consumption. For the user association problem, we propose an optimal energy-efficient user association policy and further present a distributed implementation with provable convergence. For the BS operation problem (i.e., BS switching on/off), which is a challenging combinatorial problem, we propose simple greedy-on and greedy-off algorithms that are inspired by the mathematical background of submodularity maximization problem. Moreover, we propose other heuristic algorithms based on the distances between BSs or the utilizations of BSs that do not impose any additional signaling overhead and thus are easy to implement in practice. Extensive simulations under various practical configurations demonstrate that the proposed user association and BS operation algorithms can significantly reduce energy consumption.

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Base Station Operation and User Association Mechanisms for Energy-Delay Tradeoffs in Green Cellular Networks

A majority of people now have a digital mobile device whether it be a cell phone, laptop, or blackberry. Now that we have the mobility we want it to be more versatile and dependable; RF power amplifiers accomplish just that. These amplifiers take a small input and make it stronger and larger creating a wider area of use with a more robust signal.Switching mode RF amplifiers have been theoretically possible for decades, but were largely impractical because they distort analog signals until they are unrecognizable. However, distortion is not an issue with digital signals-like those used by WLANs and digital cell phones-and switching mode RF amplifiers have become a hot area of RF/wireless design. This book explores both the theory behind switching mode RF amplifiers and design techniques for them. *Provides essential design and implementation techniques for use in cma2000, WiMAX, and other digital mobile standards*Both authors have written several articles on the topic and are well known in the industry*Includes specific design equations to greatly simplify the design of switchmode amplifiers

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Switchmode RF power amplifiers

In modern wireless communication systems, it is very important to realize simultaneously high-efficiency and linear operation of power amplifiers. This paper-overview describes the historical aspect of the Doherty approach to the power-amplifier design introduced in 1936 and modern trends in Doherty amplifier (DA) design techniques using multistage and asymmetric multiway architectures. To increase efficiency over the power backoff range, the switchmode class-E, conventional class-F, or inverse class-F operation mode by controlling the second and third harmonics can be used in the load network. The DA with a series-connected load, and inverted, push–pull, balanced, and parallel Doherty architectures are also described and discussed. Finally, examples of the lumped DA implemented in monolithic microwave integrated circuits, digitally driven Doherty technique, and broadband capability of the two-stage DA are given.

High-Efficiency Doherty Power Amplifiers: Historical Aspect and Modern Trends

PREFACE ACKNOWLEDGMENTS Chapter 1: Two-Port Network Parameters Chapter 2: Nonlinear Circuit Design Methods Chapter 3: Nonlinear Active Device Modeling Chapter 4: Impedance Matching Chapter 5: Power Transformers, Impedence Transformers, and Directional Couplers Chapter 6: Power Amplifier Design Fundamentals Chapter 7: High Efficiency Power Amplifier Design Chapter 8: Broadband Power Amplifiers Chapter 9: Power Amplifier Design for Communication Systems INDEX

RF and Microwave Power Amplifier Design

In this paper, a new circuit configuration of switched-mode tuned Class E power amplifiers with load network consisting of a parallel capacitance, a parallel inductance and a series resonant circuit tuned on the fundamental is defined using a detailed analytical description with a complete set of the design equations. The ideal collector voltage and current waveforms demonstrate a possibility of 100-percent efficiency. The circuit schematic of a parallel-circuit Class E power amplifier can be realized with lumped or transmission-line elements. Two examples of high power LDMOSFET and low-voltage HBT power amplifiers, utilizing a parallel-circuit Class E circuit configuration, are presented.

Class E with parallel circuit - a new challenge for high-efficiency RF and microwave power amplifiers

About the Author. Preface. Acknowledgements. 1 Nonlinear circuit design methods. 1.1 Spectral-domain analysis. 1.2 Time-domain analysis. 1.3 Newton-Raphson algorithm. 1.4 Quasilinear method. 1.5 Van der Pol method. 1.6 Computer-aided analysis and design. References. 2 Oscillator operation and design principles. 2.1 Steady-state operation mode. 2.2 Start-up conditions. 2.3 Oscillator configurations and historical aspects. 2.4 Self-bias condition. 2.5 Oscillator analysis using matrix techniques. 2.6 Dual transistor oscillators. 2.7 Transmission-line oscillator. 2.8 Push-push oscillator. 2.9 Triple-push oscillator. 2.10 Oscillator with delay line. References. 3 Stability of self-oscillations. 3.1 Negative-resistance oscillator circuits. 3.2 General single-frequency stability condition. 3.3 Single-resonant circuit oscillators. 3.4 Double-resonant circuit oscillator. 3.5 Stability of multi-resonant circuits. 3.6 Phase plane method. 3.7 Nyquist stability criterion. 3.8 Start-up and stability. References. 4 Optimum design and circuit technique. 4.1 Empirical optimum design approach. 4.2 Analytic optimum design approach. 4.3 Parallel feedback oscillators. 4.4 Series feedback bipolar oscillators. 4.5 Series feedback MESFET oscillators. 4.6 High-efficiency design technique. 4.7 Practical oscillator schematics. References. 5 Noise in oscillators. 5.1 Noise figure. 5.2 Flicker noise. 5.3 Active device noise modelling. 5.4 Oscillator noise spectrum: linear model. 5.5 Oscillator noise spectrum: nonlinear model. 5.6 Loaded quality factor. 5.7 Amplitude-to-phase conversion. 5.8 Oscillator pulling figure. References. 6 Varactor and oscillator frequency tuning. 6.1 Varactor modelling. 6.2 Varactor nonlinearity. 6.3 Frequency modulation. 6.4 Anti-series varactor pair. 6.5 Tuning linearity. 6.6 Reactance compensation technique. 6.7 Practical VCO schematics. References. 7 CMOS voltage-controlled oscillators. 7.1 MOS varactor. 7.2 Phase noise. 7.3 Flicker noise. 7.4 Tank inductor. 7.5 Circuit design concepts and technique. 7.6 Implementation technology issues. 7.7 Practical schematics of CMOS VCOs. References. 8 Wideband voltage-controlled oscillators. 8.1 Main requirements. 8.2 Single-resonant circuits with lumped elements. 8.3 Double-resonant circuit with lumped elements. 8.4 Transmission line circuit realization. 8.5 VCO circuit design aspects. 8.6 Wideband nonlinear design. 8.7 Dual mode varactor tuning. 8.8 Practical RF and microwave wideband VCOs. References. 9 Noise reduction techniques. 9.1 Resonant circuit design technique. 9.2 Low-frequency loading and feedback optimization. 9.3 Filtering technique. 9.4 Noise-shifting technique. 9.5 Impedance noise matching. 9.6 Nonlinear feedback loop noise suppression. References. Index.

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Andrei Grebennikov

Papers

Switchmode RF power amplifiers

High-Efficiency Doherty Power Amplifiers: Historical Aspect and Modern Trends

RF and Microwave Power Amplifier Design

Class E with parallel circuit - a new challenge for high-efficiency RF and microwave power amplifiers

RF and Microwave Transistor Oscillator Design