BOOSTING THE ENERGY EFFICIENCY IN RF POWER AMPLIFIERS

Transcription

1 BOOSTING THE ENERGY EFFICIENCY IN RF POWER AMPLIFIERS SCOPE AND BENEFITS Miroslav Vasić Universidad Politecnica de Madrid Oscar Garcia Universidad Politecnica de Madrid Jose Antonio Cobos Universidad Politecnica de Madrid Energy efficiency is the most important driver in the today s wireless industry. Due to complex signal modulations that are used, the transmitter signals have a varying envelope and the classical linear PA solutions suffer from very low efficiency (as low as only 30%). In this seminar we present and explain in detail the efficiency problem that exists in the modern RF transmitters and solutions that are used in order to resolve it. Later on, the seminar is concentrated on techniques such as Envelope Tracking (ET) and Envelope Elimination and Restoration (EER). These techniques have emerged in the last decade as the most interesting ones due to fast development of high frequency semiconductor devices and digital control. Using these techniques it is possible to obtain a highly efficient and linear Radio Frequency Power Amplifiers (RFPA) cutting the system power losses for 30%-50%. All this is possible thanks to a DC-DC converter called Envelope Amplifier that has to supply RF PAs with a voltage proportional to the signal s envelope. The main objective of this tutorial is to present the technique of envelope tracking to wide audience and explain in detail all the possible benefits and bottle necks of this approach. CONTENTS 1. State of the Art of the Modern Radio Frequency Power Amplifiers (RFPA) (duration: Modern communications 1.2. Linear amplifiers Efficiency problem 1.3. Alternatives to classical linear amplifiers Doherty Outphasing Envelope Tracking (ET) Envelope Elimination and Restoration (ERR) 2. Reducing RFPA power consumption with an Envelope amplifier (duration: Requirements 2.2. Topologies overview 2.3. Power-bandwidth trade-off 3. Review and optimization of topologies for Envelope Amplifier (duration: PWM solutions Single phase converter Multiphase converter Three level PWM converter Ripple cancellation 3.2. Dc-dc switching converter in parallel with a linear regulator EPE guidelines for tutorials 1

2 3.3. Multilevel converter in series with a linear regulator Voltages generation 3.4. Multi-input PWM converters 4. How to select optimum architecture? Design examples and comparison (duration: Single phase switching converter 4.2. Multiphase switching converter 4.3. Dc-dc switching converter in parallel with a linear regulator 4.4. Multilevel converter in series with a linear regulator 5. Integration of envelope amplifier with RF PA (duration: Problem of linearity in ET/EER based RF PA 5.2. Necessity of digital control timing alignment 5.3. Linearizing an RF PA -Predistortion technique 6. Conclusions and quantification of the Power Savings (duration:10 Monday, 5 September Tutorial day (Location: KIT, Karlsruhe, Germany) 14:00-15:30 Afternoon Tutorial Part 1 15:30-16:00 Coffee break 16:00-17:30 Afternoon Tutorial Part 2 WHO SHOULD ATTEND This tutorial is interesting to beginners and advanced participants from university and industry as it includes a perfect mixture of different aspects of power electronics for envelope tracking solutions. The tutorial comprises theoretical parts on power electronic topologies and control structures as well as practical aspects on design consideration. Technical Level: The seminar is organized for the audience with entry and intermediate level. EPE guidelines for tutorials 2

3 ABOUT THE INSTRUCTORS Miroslav Vasić was born in 1981 in Serbia. He obtained the BE at University of Belgrade, Serbia, in The Ms. and PhD he obtained at Universidad Politecnica de Madrid (UPM), Spain, in 2007 and 2010 respectively. Currently he is a post doc researcher at UPM. His areas of interest are dc-dc converters, power converters for RF applications and optimizations of converter topologies and he published more than 50 papers in IEEE journals and conferences. He advised one PhD thesis and holds one patent. In 2012 he received the SEMIKRON Innovation Award for the team work in for the teamwork on RF Power Amplifier with Increased Efficiency and Bandwidth. In 2015 he received a medal from Spanish Royal Academy of Engineering for his research trajectory as a young researcher. In 2016 Universidad Politecnica de Madrid gave him the Best Young Researcher Award. He has been cooperating with the IEEE and other professional associations as a Reviewer and a session Chair. EPE guidelines for tutorials 3

4 Oscar García (M 99) was born in Madrid, Spain, in He obtained the Ms and Ph.D. at Universidad Politecnica de Madrid (UPM) in 1992 and 1999 respectively. He is a Full Professor at the same Universidad. During his professional activity, he has been very active in the power electronics field, especially in DC-DC converters and AC-DC power factor correction. He has been involved in more than 75 research projects, holds 8 patents and he has published more than 200 technical papers mainly in IEEE conferences and journals. He received the UPM Research and Development Award for faculty less than 35 years in year 2003 and the UPM Innovation in Education Award in year He is vice-president of the Center for Industrial Electronics (CEI-UPM). He has taught several important international seminars. It can be highlighted two IEEE APEC Professional Education Seminars: - APEC 02: An Overview of Single-Phase and Three-Phase Power Factor Correction Methods for Switching Converters, together with prof. Prasad Enjeti (Texas A&M). - APEC 06: Keeping an Eye on Digital Control, together with prof. José A. Cobos and A. de Castro (both UPM). EPE guidelines for tutorials 4

5 Jose A. Cobos (M 92 SM 12) received the M.Sc. and Ph.D. degrees in electrical engineering from the Universidad Politecnica de Madrid (UPM), Madrid, Spain, in 1989 and 1994, respectively. He has been a Professor at UPM since His contributions are focused in the field of power supply systems for telecom, aerospace, industrial, automotive, and medical applications. His research interests include energy efficiency in microprocessors and RF amplifiers, magnetic components, piezoelectric transformers, transcutaneous energy transfer, and dynamic power management. He advised 14 Doctoral dissertations, he published more than 200 technical papers, and holds six patents. Dr. Cobos received the UPM Research and Development Award for faculty less than 35 years of age, and the Richard Bass Outstanding Young Power Electronics Award of the IEEE in He recently received the Semikron Innovation Award for the teamwork on RF Power Amplifier with Increased Efficiency and Bandwidth. He is the Director of the Centro de Electronica Industrial, UPM, a university research center, leading a strong industrial program in power electronics, with technology transfer through more than 50 direct R&D contracts with companies in Europe, U.S., Australia, and China. He has been cooperating with the IEEE and other professional associations as a Reviewer, session Chair, topic Chair, and Associate Editor. Since 2003, Dr. Cobos has been serving as an Associate Editor of the IEEE TRANSACTIONS ON POWER ELECTRONICS. From 2002 to 2005, he served as AE of the IEEE-PELS Letters. He is the AdCom Member of the IEEE Power Electronics Society and a Member of the Steering committee of IEEE-APEC EPE guidelines for tutorials 5