Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.

IEEE Transactions on Microwave Theory and Techniques and Antennas and Propagation Announce a Joint Special Issue on Ultra-Wideband (UWB) Technology

This paper presents a comparative overview of the most important approaches presented to address the behavioral modeling of microwave and wireless power amplifiers (PAs). Starting from a theoretical framework of recursive and nonrecursive nonlinear filters, it proposes a classification of the various PA behavioral models, discussing their abilities to represent the different effects observed in practical circuits. Using that formal procedure, one explains how it was possible to integrate a wide range of behavioral modeling activities and to show that some of them, which at first glance seemed to be quite different, are, indeed, identical in their modeling capabilities.

A comparative overview of microwave and wireless power-amplifier behavioral modeling approaches

A new representation of the Volterra series is proposed, which is derived from a previously introduced modified Volterra series, but adapted to the discrete time domain and reformulated in a novel way. Based on this representation, an efficient model-pruning approach, called dynamic deviation reduction, is introduced to simplify the structure of Volterra-series-based RF power amplifier behavioral models aimed at significantly reducing the complexity of the model, but without incurring loss of model fidelity. Both static nonlinearities and different orders of dynamic behavior can be separately identified and the proposed representation retains the important property of linearity with respect to series coefficients. This model can, therefore, be easily extracted directly from the measured time domain of input and output samples of an amplifier by employing simple linear system identification algorithms. A systematic mathematical derivation is presented, together with validation of the proposed method using both computer simulation and experiment

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Dynamic Deviation Reduction-Based Volterra Behavioral Modeling of RF Power Amplifiers

Preface. About the Authors. Acknowledgments. 1 Power Amplifier Fundamentals. 1.1 Introduction. 1.2 Definition of Power Amplifier Parameters. 1.3 Distortion Parameters. 1.4 Power Match Condition. 1.5 Class of Operation. 1.6 Overview of Semiconductors for PAs. 1.7 Devices for PA. 1.8 Appendix: Demonstration of Useful Relationships. 1.9 References. 2 Power Amplifier Design. 2.1 Introduction. 2.2 Design Flow. 2.3 Simplified Approaches. 2.4 The Tuned Load Amplifier. 2.5 Sample Design of a Tuned Load PA. 2.6 References. 3 Nonlinear Analysis for Power Amplifiers. 3.1 Introduction. 3.2 Linear vs. Nonlinear Circuits. 3.3 Time Domain Integration. 3.4 Example. 3.5 Solution by Series Expansion. 3.6 The Volterra Series. 3.7 The Fourier Series. 3.8 The Harmonic Balance. 3.9 Envelope Analysis. 3.10 Spectral Balance. 3.11 Large Signal Stability Issue. 3.12 References. 4 Load Pull. 4.1 Introduction. 4.2 Passive Source/Load Pull Measurement Systems. 4.3 Active Source/Load Pull Measurement Systems. 4.4 Measurement Test-sets. 4.5 Advanced Load Pull Measurements. 4.6 Source/Load Pull Characterization. 4.7 Determination of Optimum Load Condition. 4.8 Appendix: Construction of Simplified Load Pull Contours through Linear Simulations. 4.9 References. 5 High Efficiency PA Design Theory. 5.1 Introduction. 5.2 Power Balance in a PA. 5.3 Ideal Approaches. 5.4 High Frequency Harmonic Tuning Approaches. 5.5 High Frequency Third Harmonic Tuned (Class F). 5.6 High Frequency Second Harmonic Tuned. 5.7 High Frequency Second and Third Harmonic Tuned. 5.8 Design by Harmonic Tuning. 5.9 Final Remarks. 5.10 References. 6 Switched Amplifiers. 6.1 Introduction. 6.2 The Ideal Class E Amplifier. 6.3 Class E Behavioural Analysis. 6.4 Low Frequency Class E Amplifier Design. 6.5 Class E Amplifier Design with 50# Duty-cycle. 6.6 Examples of High Frequency Class E Amplifiers. 6.7 Class E vs. Harmonic Tuned. 6.8 Class E Final Remarks. 6.9 Appendix: Demonstration of Useful Relationships. 6.10 References. 7 High Frequency Class F Power Amplifiers. 7.1 Introduction. 7.2 Class F Description Based on Voltage Wave-shaping. 7.3 High Frequency Class F Amplifiers. 7.4 Bias Level Selection. 7.5 Class F Output Matching Network Design. 7.6 Class F Design Examples. 7.7 References. 8 High Frequency Harmonic Tuned Power Amplifiers. 8.1 Introduction. 8.2 Theory of Harmonic Tuned PA Design. 8.3 Input Device Nonlinear Phenomena: Theoretical Analysis. 8.4 Input Device Nonlinear Phenomena: Experimental Results. 8.5 Output Device Nonlinear Phenomena. 8.6 Design of a Second HT Power Amplifier. 8.7 Design of a Second and Third HT Power Amplifier. 8.8 Example of 2nd HT GaN PA. 8.9 Final Remarks. 8.10 References. 9 High Linearity in Efficient Power Amplifiers. 9.1 Introduction. 9.2 Systems Classification. 9.3 Linearity Issue. 9.4 Bias Point Influence on IMD. 9.5 Harmonic Loading Effects on IMD. 9.6 Appendix: Volterra Analysis Example. 9.7 References. 10 Power Combining. 10.1 Introduction. 10.2 Device Scaling Properties. 10.3 Power Budget. 10.4 Power Combiner Classification. 10.5 The T-junction Power Divider. 10.6 Wilkinson Combiner. 10.7 The Quadrature (90 ) Hybrid. 10.8 The 180 Hybrid (Ring Coupler or Rat-race). 10.9 Bus-bar Combiner. 10.10 Other Planar Combiners. 10.11 Corporate Combiners. 10.12 Resonating Planar Combiners. 10.13 Graceful Degradation. 10.14 Matching Properties of Combined PAs. 10.15 Unbalance Issue in Hybrid Combiners. 10.16 Appendix: Basic Properties of Three-port Networks. 10.17 References. 11 The Doherty Power Amplifier. 11.1 Introduction. 11.2 Doherty's Idea. 11.3 The Classical Doherty Configuration. 11.4 The 'AB-C' Doherty Amplifier Analysis. 11.5 Power Splitter Sizing. 11.6 Evaluation of the Gain in a Doherty Amplifier. 11.7 Design Example. 11.8 Advanced Solutions. 11.9 References. Index.

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High Efficiency RF and Microwave Solid State Power Amplifiers

A comparative study of state-of-the-art behavioral models for microwave power amplifiers (PAs) is presented in this paper. After establishing a proper definition for accuracy and complexity for PA behavioral models, a short description on various behavioral models is presented. The main focus of this paper is on the modeling accuracy as a function of computational complexity. Data is collected from measurements on two PAs-a general-purpose amplifier and a Doherty PA designed for WiMAX-for different output power levels. The models are characterized in terms of accuracy and complexity for both in-band and out-of-band error. The results show that, among the models studied, the generalized memory polynomial behavioral model has the best tradeoff for accuracy versus complexity for both PAs, and can obtain high performance at half of the computational cost of all other models analyzed.

https://publications.lib.chalmers.se/records/fulltext/local_121905.pdf

A Comparative Analysis of the Complexity/Accuracy Tradeoff in Power Amplifier Behavioral Models

A new approach to the approximation of nonlinear characteristics for look-up table based electron device models is proposed. It relys on the strong analogy between signal sampling and characteristic measurements over a discrete grid of bias points. On this basis, nonlinear function approximation can be carried out by using approaches similar to well-known techniques for reconstruction of continuous-time signals from a given sequence of samples. With respect to conventional interpolation techniques, the method proposed guarantees the accurate reproduction both of nonlinear characteristics and as­sociated derivatives without non physical slopes or oscillating behaviour. Preliminary simulated and experimental results confirming the effectiveness of this approach are presented.

A signal-theory based approach for the approximation of electron device characteristics

This chapter aims to describe methodologies and techniques for de-embedding device measurements from extrinsic measurements by characterizing the parasitic network surrounding the intrinsic device, through the use of a three-dimensional (3D) physical model of the network and its electromagnetic (EM) analysis. The electromagnetic behavior is obtained employing 3D EM solvers and internal ports. In the first part, the de-embedding processes for field-effect transistor (FET) devices to be used for monolithic microwave integrated circuit designs are studied by four different approaches; in the second part of this chapter, the de-embedding of FET devices for hybrid circuit design purposes is described.

Electromagnetic-Analysis-Based Transistor De-embedding and Related Radio-Frequency Amplifier Design

A previously proposed approach for modelling the dispersive effects in III-V FET devices is applied to InP and GaAs HEMTs in order to verify its validity also for heterostructure-based devices and to confirm its technology independence. Both surface states, bulk traps and thermal dispersive phenomena are simultaneously taken into account to allow for a better prediction of the deviations between dynamic (e.g., pulsed) and static drain current characteristics.

Modelling of low-frequency dispersive effects in GaAs and InP HEMTs

The extraction of accurate transistor models is essential for a reliable and efficient design of transmit/receive modules, which in turn is a keystone for the development of active electronically scanned array radars The present paper is aimed at analysing the implementation of non-quasi-static effects for advanced millimeter-wave FET models The non-quasi-static phenomena can be neglected at few GHz but their contributions become more and more dominant by increasing the operating frequencies In particular, this study is focused on the investigation of the non-quasi-static effects for modeling the intrinsic short circuit output admittance for FETs based on gallium nitride, silicon, and gallium arsenide technologies Different model solutions are carefully compared and analysed in detail

http://ieeexplore.ieee.org/iel5/5606056/5614805/05614993.pdf

Non-quasi-static modeling of the intrinsic Y 22 for GaN, Si, and GaAs mm-wave FET technologies

New system architectures oriented to more and more challenging performance for the next generations of mobile devices demand for an accurate design of integrated circuits. The power amplifier is one of the most critical components in an RF system and the need for high performance has focused the designer attention to complex architectures, such as the Doherty power amplifier (DPA). In its most common implementations, the design requires transistor models showing high-accuracy levels under different classes of operation. In this work, we investigate the possibility of achieving the required level of accuracy for the transistor current-generator model using a set of measurements performed under the different classes of operation that mimic realistic device operation and use them for the model optimization. The developed approach is fully validated on a 28-GHz MMIC DPA, showing good agreement with the measured results.

Giorgio Vannini

Papers

A signal-theory based approach for the approximation of electron device characteristics

Electromagnetic-Analysis-Based Transistor De-embedding and Related Radio-Frequency Amplifier Design

Modelling of low-frequency dispersive effects in GaAs and InP HEMTs

Non-quasi-static modeling of the intrinsic Y 22 for GaN, Si, and GaAs mm-wave FET technologies

Empowering GaN-Si HEMT Nonlinear Modelling for Doherty Power Amplifier Design