Diplexing Distributed Power Amplifier for Mobile
Transcrição
Diplexing Distributed Power Amplifier for Mobile
Diplexing Distributed Power Amplifier for Mobile Applications Der Technischen Fakultät der Universität Erlangen-Nürnberg zur Erlangung des Grades DOKTOR-INGENIEUR Vorgelegt von M. Sc. Wei Wang Erlangen, März 2012 Verteilte Mehrtor Leistungsverstärker für Mobilfunkanwendungen mit Diplexerfunktion Als Dissertation genehmigt von der Technischen Fakultät der Universität Erlangen-Nürnberg Tag der Einreichung: 11. 08. 2011 Tag der Promotion: 19. 03. 2012 Dekanin: Prof. Dr.-Ing. Marion Merklein Berichterstatter: Prof. Dr.-Ing. Georg Fischer Prof. Dr.-Ing. Wolfgang Heinrich Berichte aus der Kommunikationstechnik Wei Wang Diplexing Distributed Power Amplifier for Mobile Applications D 29 (Diss. Universität Erlangen-Nürnberg) Shaker Verlag Aachen 2012 Bibliographic information published by the Deutsche Nationalbibliothek The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available in the Internet at http://dnb.d-nb.de. Zugl.: Erlangen-Nürnberg, Univ., Diss., 2012 Copyright Shaker Verlag 2012 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publishers. Printed in Germany. ISBN 978-3-8440-1167-8 ISSN 0945-0823 Shaker Verlag GmbH • P.O. BOX 101818 • D-52018 Aachen Phone: 0049/2407/9596-0 • Telefax: 0049/2407/9596-9 Internet: www.shaker.de • e-mail: [email protected] Acknowledgements My foremost appreciation goes to Mr. Christian Korden at TDK-EPC Corporation, Munich and Prof. Dr.-Ing. Robert Weigel, the Chair of Electronics Engineering at University of Erlangen-Nuremberg, Germany. They gave me the opportunity to work on this interesting topic. I also wish to express my gratitude to Prof. Dr.-Ing. Georg Fischer, who has supervised me throughout my work. Without his helpful guidance and instruction I wouldn’t have finished my dissertation. My sincere thanks also go to Dr. Ir. Léon van den Oever at Radio Semiconductor B.V. Nijmegen, the Netherlands. As one of the most experienced engineers in the field of mobile phone power amplifier, he always gave me valuable suggestions and instructions. Furthermore, I would like to thank my colleagues at the chair of Electronics Engineering at the University of Erlangen-Nuremberg and at TDK-EPC Corporation for all their assistance during my PhD study. Finally I would like express my appreciation to my parents and wife for their support, understanding and love. I Abstract For the purpose of multiband mobile phone power amplifier (PA) design, the prospect of using a distributed amplifier (DA) has been investigated, which over the last 50 years is well known for its excellent broadband behaviour. In order to better adapt the DA to mobile phone PA applications, a new concept is proposed, namely the linear diplexing tapered DA. To verify this concept, the following designs have been investigated: x x Single stage PCB demonstrator Two-stage on-chip design, which has tapered DA as driver and the diplexing tapered DA as a final PA stage Due to the unique properties of the (diplexing tapered) DA, some commonly used techniques in Single-Ended-PA designs are not applicable. Therefore modifications and adaptations are made. Furthermore, the supplementary properties of the diplexing tapered DA are discussed: x x x x Stage bypass for PAE enhancement of DA during large back-off (BO) operation Due to multiple feedback loops and nonlinear devices, large signal and parametric stability are characterised by system identification method Due to the inferior linearity of DA, a special dynamic biasing circuit to compensate for the gain expansion is proposed The ability to apply spectrum aggregation and load balancing techniques II Kurzfassung In der vorliegenden Arbeit wurde für die im Mobilfunk eingesetzten Multibandleistungsverstärker (Multiband PA) die Verwendung von verteilten Verstärker (Distributed Amplifier - DA) untersucht, die seit langem für ihre ausgezeichnete Breitbandigkeit bekannt sind. Als neues Konzept wurde der linear verteilte Mehrtorverstärker mit Diplexerfunktion verwendet. Zur Überprüfung der Funktionsweise wurde ein einstufiger PCB-Demonstrator mit diskreten Bauteilen aufgebaut und charakterisiert, sowie ein zweistufiges IC-Design mit einem tapered DA als Treiber und einem tapered Mehrtor-DA mit Diplexerfunktion als Endstufe verifiziert. Aufgrund der speziellen Eigenschaften von verteilten Verstärkern mit Diplexerfunktion lassen sich einige bekannte und häufig verwendete Techniken zur Verbesserung von Linearität und Wirkungsgrad - wie sie häufig zur Auslegung von Single-Ended-PAs verwendet werden, nicht anwenden. Daher wurden folgende Techniken adaptiert und neu in Schaltung und Simulation eingeführt: x x x x Bypass-Stufe zur Erhöhung des Verstärkerwirkungsgrads (PAE) im Back-Off (BO) Analyse der parametrischen und Großsignalstabilität Dynamische Bias-Schaltung zur Linearitätsverbesserung bzw. zur Kompensation der Verstärkungsexpansion Berücksichtigung von Last-Balancierung- und Spektrum-Aggregationstechniken III Table of contents Acknowledgements ................................................................................................................................ I Abstract.................................................................................................................................................II List of abbreviations ........................................................................................................................... VI 1. Introduction................................................................................................................................... 1 2. Power amplifier fundamentals ...................................................................................................... 3 2.1. Efficiency ....................................................................................................................... 4 2.1.2. Gain ................................................................................................................................ 4 2.1.3. Maximal output power and back-off .............................................................................. 5 2.1.4. Linearity ......................................................................................................................... 6 2.2. 3. Operation class comparison: Class A and Class AB .............................................................. 9 The power amplifier bandwidth .................................................................................................. 12 3.1. Transistor’s figure of merits ................................................................................................. 12 3.2. Matching limitation.............................................................................................................. 14 3.2.1. Bode-Fano limit ........................................................................................................... 14 3.2.2. Limitation of LC matching ........................................................................................... 15 3.3. 4. PA characteristics .................................................................................................................. 3 2.1.1. Broadband amplifier topologies ........................................................................................... 18 3.3.1. Common source (CS) amplifier .................................................................................... 19 3.3.2. Lossy matched (LM) amplifier ..................................................................................... 19 3.3.3. Shunt negative feedback (FB) amplifier ....................................................................... 20 3.3.4. Balanced amplifier (BA) .............................................................................................. 20 3.3.5. Distributed amplifier (DA) ........................................................................................... 21 3.3.6. Comparison of topologies............................................................................................. 21 PAE enhancement method .......................................................................................................... 26 4.1. Dynamic bias ....................................................................................................................... 26 4.2. Stage bypass in different circuit topologies.......................................................................... 28 4.2.1. Stage bypass in conventional multistage PA ................................................................ 28 4.2.2. Linear switched Doherty amplifier ............................................................................... 29 4.2.3. Stage bypass in BA. ..................................................................................................... 30 4.2.4. Distinguished stage bypass in DA ................................................................................ 31 4.3. Spectrum aggregation and load balancing ............................................................................ 31 IV 5. 6. Distributed Amplifier for mobile phone ...................................................................................... 34 5.1. Introduction ......................................................................................................................... 34 5.2. Design procedure of tapered DA.......................................................................................... 35 5.3. The linearity of DA .............................................................................................................. 38 5.4. Stability consideration ......................................................................................................... 39 5.5. Distinguished stage bypass in DA........................................................................................ 43 Directional Distributed Amplifier based on CRLH structure ...................................................... 48 6.1. CRLH-TL ............................................................................................................................ 48 6.2. The diplexing DA ................................................................................................................ 49 6.3. Linear tapered diplexing DA................................................................................................ 51 6.4. Circuit application discussion .............................................................................................. 56 6.5. PCB demonstrator ................................................................................................................ 56 6.5.1. Circuit description ........................................................................................................ 57 6.5.2. Measurement results ..................................................................................................... 58 6.6. 6.6.1. Circuit description ........................................................................................................ 66 6.6.2. Simulation results ......................................................................................................... 68 6.7. 7. On-chip demonstrator .......................................................................................................... 66 Triplexing and multiplexing DA opportunity....................................................................... 71 Conclusions and future work ...................................................................................................... 74 Appendix A: The mathematical expression of IMD............................................................................ 76 Appendix B: The system identification process .................................................................................. 77 Biboliography ..................................................................................................................................... 80 Author’s publications .......................................................................................................................... 88 V List of abbreviations AC Alternating Current ACLR Adjacent Channel Leakage Ratio ACPR Adjacent Channel Power Ratio ADS Advanced Design System AV Low frequency voltage gain BO Back-off level BW Band Width C Capacitance CRLH Composite Right/Left- Handed structure DA Distributed Amplifier DC Direct Current EM ElectroMagnetic EVM Error Vector Magnitude FEM Front End Module FET Field Effect Transistor fmax Maximal oscillation frequency ft Maximal transit frequency GaAs Gallium Arsenide GSM Global System for Mobile Communications GT Transducer power gain HB Harmonic Balance or High Band HBT Hetrojunction Bipolar Transistor HSPA High Speed Package Access I Current IM Intermodulation VI IMN Input Matching Network ISO Isolation LB Low Band LH Left Handed structure LSG Large Signal Gain LTE Long Term Evolution MAG Maximal Available Gain MEMS Micro- Electro Mechanical System OFDM Orthogonal Frequency Division Multiplexing OMN Output Matching Network PA Power Amplifier PAE Power Added Efficiency PCB Printed Circuit Board PHEMT Pseudo High Electron Mobility Transistor Q Quality factor QAM Quadrature Amplitude Modulation QPSK Quadrature Phase Shift Keying RF Radio Frequency RH Right Handed structure RX Transceiver SC-FDMA Single Carrier Frequency Division Multiple Access SDR/CR Software Defined Radio/Cognitive Radio TX Transmitter TL Transmission Line TWA Travelling Wave Amplifier UMTS Universal Mobile Telecommunications System Vcc Supply Voltage VII VSWR Voltage Standing Wave Ratio WCDMA Wideband Code Division Multiple Access WLAN Wireless Local Area Network Z0 Characteristic impedance β Propagation constant Γ Reflecting coefficient ηD Drain efficiency λ Wavelength θ Phase shift ω Angular frequency VIII