ZTE

ZTE Communications ›› 2011, Vol. 9 ›› Issue (3): 13-21.

• Special Topic • Previous Articles     Next Articles

A New Two-Branch Amplification Architecture and its Application with Various Modulated Signals

W. Hamdane, A. B. Kouki, and F. Gagnon   

  1. Department of Electrical Engineering, école de Technologie Supérieure, Montréal, Québec H3C 1K3, Canada
  • Online:2011-09-25 Published:2011-09-25
  • About author:Walid Hamdane (walid.hamdane.1@ens.etsmtl.ca) received his B.Eng. degree in electrical engineering from école Polytechnique de Tunisie and his Ph.D. degree in electrical engineering from école de Technologie Supérieure, Montréal. His research interests include power efficiency enhancement for wireless transmitters, advanced transmitter design for modern radio applications, and frequency synthesizers for radar applications design. From 2008 to 2009, he was a power amplifier designer with Mitec Telecom Inc. Currently, he is an RF hardware engineer at Nanowave Technologies Inc and works with the signal source group. He has 10 publications and 2 patents (pending). Dr. Hamdane was awarded postgraduate scholarships (2004-2008) from the Tunisian Ministry of Higher Education and has been awarded several distinctions.

    Ammar B. Kouki (ammar.kouki@etsmtl.ca) received his B.S. (with honors) and M.S. degrees in engineering science from Pennsylvania State University in 1985 and 1987. He received his Ph.D. degree in electrical engineering from the University of Illinois at Urbana-Champaign in 1991. Between 1988 and 1991, he was a consultant at the National Center for Supercomputing Applications (NCSA). From 1991 to 1993, he was a postdoctoral fellow at the Microwave Research Laboratory, école Polytechnique de Montréal. From 1994 to 1998, he was a senior microwave engineer at the same laboratory and was involved with power amplifier linearization techniques. In 1998, he co-founded AmpliX Inc., a company that specialized in RF linearizers for wireless and SatCom applications. In 1998, he joined the faculty of the école de Technologie Supérieure, Montréal, where he is currently full professor of electrical engineering and director of the LACIME laboratory. He was also one of the co-founders of ISR Technologies, a software defined radio company. Professor Kouki has written more than 160 peer-reviewed papers and holds six patents (three are currently under review). He has diverse research interests that cover radio communication and navigation with a focus on devices, intelligent and efficient RF front ends/transceiver architectures, and antenna and propagation. He is currently researching active device modeling and characterization, power-amplifier design, linearization, and efficiency enhancement techniques. He is also involved in computational electromagnetic techniques for modeling and designing passive microwave structures and is active in multiple antenna systems and intelligent antenna research.

    Fran?ois Gagnon (francois.gagnon@etsmtl.ca) received his B.Eng. and Ph.D. degrees in electrical engineering from école Polytechnique de Montréal. Since 1991, he has been a professor in the Department of Electrical Engineering, école de Technologie Supérieure, Montréal. He chaired the department from 1999 to 2001 and is now the holder of the NSERC Ultra Electronics Chair, Wireless Emergency and Tactical Communication, at the same university. His research interests include wireless high-speed communications, modulation, coding, high-speed DSP implementations, and military point-to-point communications. He has been heavily involved in creating the new generation of high-capacity line-of-sight military radios offered by the Canadian Marconi Corporation (now Ultra Electronics Tactical Communication Systems). The company received, a Coin of Excellence from the U.S. Army for the performance and reliability of the radio product. Professor Gagnon is a recognized leader in research management. With an annual budget of $1.6M, he supervises 18 graduate students, leads a team of seven research professionals, and participates in activities with companies such as Ultra, ISR technology, Sita, Ericsson, Lipso, Nortel, Bell, Octasic Semiconductors, Sierra Wireless, Boomerang, and IREQ. Professor Gagnon was awarded the 2008 NSERC Synergy Award (small and medium-sized companies category) for his fruitful and long-lasting collaboration with Ultra Electronics TCS.

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Abstract: This paper proposes a new two-branch amplification architecture that combines baseband signal decomposition with RF front-end optimization. In the proposed architecture, the filtered modulated signals are separated into two components that are then amplified independently and combined to regenerate an amplified version of the original signal. A branch with an efficient amplifier transmits a low-varying envelope signal that contains the main part of the information. Another branch amplifies the residual portion of the signal. The baseband decomposition and parameters of the RF part are optimized to find the configuration that gives the best power efficiency and linearity. For M-ary quadrature amplitude modulation (M-QAM) signals, this technique is limited in terms of power efficiency. However, for filtered continuous phase modulation (CPM) signals, especially for minimum shift keying (MSK) and Gaussian MSK (GMSK) signals, high power efficiency can be achieved with no significant impact on the overall linearity. The results show that this technique gives better performance than the single-ended class-B amplifier.

Key words: CPM modulation, M-QAM, RF power amplifiers, DC-RF efficiency, linearity, crest factor, shaping filters