Wenhua Chen · Karun Rawat Fadhel M. Ghannouchi Multiband RF Circuits and Techniques for Wireless Transmitters Multiband RF Circuits and Techniques for Wireless Transmitters Wenhua Chen • Karun Rawat Fadhel M. Ghannouchi Multiband RF Circuits and Techniques for Wireless Transmitters 123 Wenhua Chen Fadhel M. Ghannouchi Tsinghua University University of Calgary Beijing Calgary, AB China Canada Karun Rawat Indian Institute of Technology Roorkee Roorkee India ISBN 978-3-662-50438-3 ISBN 978-3-662-50440-6 (eBook) DOI 10.1007/978-3-662-50440-6 Library of Congress Control Number: 2016940120 © Springer-Verlag Berlin Heidelberg 2016 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer-Verlag GmbH Berlin Heidelberg We would like to dedicate our efforts to our family who inspired and supported us through everything. We would also like to acknowledge all of our students and colleagues for their support. Contents 1 RF Amplifier Design and Architectures ..................... 1 1.1 Introduction . 1 1.2 Small-Signal Amplifier Design . 2 1.2.1 Types of Transistor Amplifier Power Gains . 2 1.2.2 Transistor Amplifier Stability . 4 1.2.3 Single-Stage Transistor AmplifierDesign............. 4 1.3 Large-Signal Amplifier Design . 7 1.3.1 PA Analytical Modeling and Figures of Merits . 7 1.3.2 PA Classes of Operations (A, B, AB, and C) . 16 1.3.3 Current and Voltage Waveforms . 19 1.3.4 Harmonic Impedance-Controlled Amplifiers........... 20 1.3.5 Continuous-Mode PAs. 23 References . 28 2 Dual-Branch RF Amplifier Design and Architectures ........... 29 2.1 Introduction . 29 2.2 Balanced Amplifiers................................. 30 2.3 Push–Pull Amplifiers................................ 32 2.3.1 Push–Pull Amplifier with Bipolar Transistors . 34 2.3.2 Push–Pull Amplifier with Baluns. 35 2.4 Doherty Amplifiers................................. 36 2.4.1 Doherty Amplifier Architecture . 36 2.4.2 Efficiency Calculation and Optimization of Doherty Amplifier................................... 37 2.5 Pulsed-Load-Modulated Amplifier....................... 39 2.5.1 Load Modulation in Switched Resonators. 40 2.5.2 PAs with Pulsed-Load Modulation . 41 2.6 Linc Amplifiers.................................... 45 2.6.1 LINC Amplifier Architecture . 45 2.6.2 Case of Matched and Isolated Combiner . 47 2.6.3 Case of Nonmatched Combiners (Chireix Combiners) . 49 vii viii Contents 2.7 Delta-Sigma-Based Transmitters . 51 2.7.1 Delta-Sigma Modulation . 51 2.7.2 DSM-Based Transmitter. 54 2.7.3 Efficiency Calculation of DSM Transmitter. 54 2.7.4 Cartesian Delta-Sigma Transmitter. 56 2.7.5 Polar Delta-Sigma Transmitter . 57 References . 58 3 Multiband RF Transmitters .............................. 59 3.1 Introduction . 59 3.2 RF Transmitters . 59 3.2.1 Conventional Single-Band Transmitter . 59 3.2.2 Multiband Transmitter . 60 3.3 Multiband Transmitter Architectures . 61 3.3.1 Multiband Doherty Transmitter . 61 3.3.2 Multiband Envelope-Tracking Transmitter . 64 3.3.3 Multiband Outphasing Transmitter. 67 3.3.4 Multiband Delta-Sigma Transmitter . 68 3.4 Multiband RF Transmitter Circuits. 69 3.4.1 Reconfigurable Multiband Transmitter . 69 3.4.2 Concurrent Multiband PA . 71 References . 78 4 Multiband RF Passive Circuits............................ 81 4.1 Introduction . 81 4.2 Fundamentals of Network Theory . 81 4.2.1 Introduction to Some Important Network Parameters Designs . 82 4.2.2 Properties of RF Networks in Terms of Network Parameters . 85 4.2.3 Image Parameters and Design of RF Networks Using ABCD Matrix . 86 4.2.4 Transmission-Line Equivalence with Image Parameters . 87 4.3 Multiband RF Transformers . 90 4.3.1 Stub-Loaded (T-Shape and Pi-Shape) Transformers . 90 4.3.2 Multisection Non-quarter-Wave Impedance Transformer . 93 4.3.3 Coupled-Line-Based Impedance Transformer . 96 4.4 Multiband Power Divider and Hybrid Design . 98 4.4.1 Multiband Wilkinson Power Divider . 98 4.4.2 Multiband Hybrid Couplers . 100 4.4.3 Multiband Frequency-Dependent Power Dividers . 106 4.5 Planar Slow-Wave Structures and Miniaturization . 113 Contents ix 4.6 Multiband Filters . 119 4.6.1 Fundamentals of RF Filter Design. 120 4.6.2 Lowpass Prototype Design . 122 4.6.3 Filter Design from Lowpass Prototype (Scaling and Frequency Transformation). 125 4.6.4 Distributed-Element Filter Realization . 132 4.6.5 Multiband Lumped-Element Filter Design . 135 4.6.6 Multiband Filter Design Using Coupling Matrix . 138 4.6.7 Reconfigurable Band Pass Filter Design . 146 References . 154 5 Multiband Power Amplifier Design......................... 157 5.1 Introduction . 157 5.2 Multiband Power Amplifier Matching . 157 5.2.1 Concurrent Matching Techniques . 158 5.2.2 Reconfigurable Matching Techniques. 169 5.3 Multiband Power AmplifierDesign...................... 172 5.3.1 Multiband Class-AB Power Amplifier Design . 172 5.3.2 Multiband Class-E Power Amplifier................ 173 5.3.3 Multiband Class-F Power Amplifier................. 179 5.4 Multiband Doherty Power Amplifier..................... 181 5.4.1 Multiband Doherty Power Amplifier Design . 186 References . 198 6 Digital Techniques for Multiband RF Transmitters ............. 203 6.1 Introduction . 203 6.2 Nonlinearities of Multiband Transmitters . 203 6.3 Two-Dimensional Digital Predistortion (2D-DPD) Technique . 207 6.3.1 2D-DPD Behavioral Model . 207 6.3.2 Model Evaluation and Results. 210 6.4 Low-Complexity 2D-DPD Techniques . 212 6.4.1 2D-Modified Memory Polynomial (2D-MMP) Model . 212 6.4.2 Adaptive Pruning Method for 2D-DPD . 223 6.5 Digital Techniques for Multiband Transmitters with Hardware Impairments . 226 6.5.1 Time-Misalignment Tolerant (TMT) Behavioral Model . 226 6.5.2 Phase-Compensated Behavioral Model. 231 6.6 Hardware Implementation for 2D-DPD with Subsampling Technique. 234 6.6.1 Subsampling Feedback Architecture . 234 6.6.2 Subsampling Frequencies Selection . 236 6.6.3 Experimental Evaluation . 238 References . 241 Chapter 1 RF Amplifier Design and Architectures 1.1 Introduction An amplifier receives a signal from an input source and provides a scaled version of the signal to an output device such as an antenna or to another amplifier stage. In small-signal amplifiers, the main factors are usually linearity, gain, and efficiency. For small-signal analysis, the amount of power handling capacity and power effi- ciency are of little concern. Large-signal devices such as power amplifiers (PAs), on the other hand, primarily provide sufficient power to an output load to drive another device, typically a few watts to tens of watts. In this chapter, we concentrate on those PA circuits that are typically used to handle large-voltage signals at moderate-to-high current levels. The main features of a large-signal PA are the power efficiency, the maximum amount of power that the circuit is capable of handling, and the linearity. There has been considerable industrial interest in producing Radio Frequency (RF) PAs with good linearity and power efficiency. These two contradictory requirements can be composed by using external circuitry to linearize an efficient amplifier. Ideally, linearity is the ability of an amplifier to maintain equal gain for any input signal. But, this is not true in practice, especially for higher input power levels. PAs must be linear to minimize interference and spectral regrowth. However, PAs have an inherent nonlinear behavior and are considered the main reason of distortions in RF transmitters. Moreover, researchers have been focusing on designing more efficient power amplification techniques. Efficiency is needed to minimize power consumption and operating costs of high-power RF transmitters. The trade-off between linearity and efficiency is well reported in the literature. The current state of the art is to design a PA with the highest possible efficiency and to implement a linearization technique to restore linearity. © Springer-Verlag Berlin Heidelberg 2016 1 W. Chen et al., Multiband RF Circuits and Techniques for Wireless Transmitters, DOI 10.1007/978-3-662-50440-6_1 2 1 RF Amplifier Design and Architectures 1.2 Small-Signal Amplifier Design For small-signal amplifiers, a linear analysis is applicable. Consequently, we can treat the transistor as a two-port network that is entirely defined by its measured scattering (S) parameters or predicted using a small-signal linear-equivalent circuit model. 1.2.1 Types of Transistor Amplifier Power Gains A generic two-port transistor identified by its S parameters (defined in a system having characteristic impedance Zo) connected to a voltage generator, Vs, having source impedance ZS and loaded with an impedance ZL, is shown in Fig. 1.1. ða1; b1Þ and ða2; b2Þ are the incident and reflected normalized voltage waves of the two-port circuit, respectively, which can be expressed as a function of the incident and reflected voltages at the two ports as follows: þ À þ À V1 V1 V2 V2 a1 ¼ pffiffiffiffiffi ; b1 ¼ pffiffiffiffiffi a2 ¼ pffiffiffiffiffi and b2 ¼ pffiffiffiffiffi ð1:1Þ Zo Zo Zo Zo þ þ À À fl where V1 and V2 are the incident voltages, and V1 and V2 are the re ected voltages at port 1 and port 2 of the transistor.