Steve C. Cripps obtained his Ph.D. degree from Cambridge University, England. He worked for Plessey Research (now GECMM) on GaAsFET hybrid circuit development. Later he joined Watkins-Johnson’s solid state division , Palo Alto, CA, and has held Engineering and Management positions at WJ, Loral, and Celeritek. During this period, he designed the industry’s first 2-8 Ghz and 6-18 Ghz 1 watt solid state amplifiers, and in 1983 published a technique for microwave power amplifier design, which has become widely adopted in the industry. In 1990 he became an independent consultant and was active in a variety of commercial RF product developments, including the design of several cellular telephone power amplifier MMIC products. In 1996 he returned to England, where his consulting activities continue to be focused in the RF power amplifier area. He has just published a second edition of his best-selling book, “RF Power Amplifier Design for Wireless Communications” (Artech House). He is currently vice-chair of the High Power Amplifier subcommittee of the Technical Co-ordination and Technical Program Committees of the IEEE Microwave Theory and Techniques Society, and writes the regular “Microwave Bytes” column in the IEEE Microwave Magazine. Dr Cripps is an IEEE fellow and a Professorial research fellow at Cardiff University, UK.
High Efficiency Amplification of Variable Envelope Signals for Modern Wireless Communications Systems: Doherty and ChireixRe-Visited
Modern wireless systems pose severe challenges for the RF PA designer, both at the mobile end, where efficiency is paramount, and at basestation, which may require multi-channel operation. Most systems use phase-shift modulation but usually have accompanying envelope variations in order to limit channel bandwidth. This talk will review the basic theory of the Doherty technique and the Chireix outphasing method for designing such future systems.