"RF Power Amplifiers: New thoughts on an old subject"
"RF POWER AMPLIFIERS: NEW THOUGHTS ON AN OLD SUBJECT (SCSAT)"
Steve C. Cripps
Time: SATURDAY, JANUARY 14, 2-6pm
RF power amplifiers have received a great deal of attention and development effort over the last decade, mainly due to the challenging requirements of the wireless communications industry. This effort has not only led to some impressive progress in PA performance, it has also led to some revisions and rethinking in traditional PA theory. These developments
will undoubtedly have an impact on PA design in all application areas, including but not restricted to wireless communications. This tutorial session will attempt to highlight some of these areas. Topics covered will include:
- Class AB PA design; to short, or not to short, the harmonics (input as well as output).
- Loadpull techniques and RF waveform measurement.
- Optimization of device characteristics for linearity and efficiency (serendipity still rules).
- What the new technologies (HBTs, high bandgap, LDMOS) bring to the PA party, and what they don’t.
- Classes D, E, F: still solutions without a problem?
- The skeletons in the PA closet: stability, bias supply. modulation, memory effects and “presdistortability.”
- Efficiency enhancement: How Polar Loop and envelope tracking techniques are gaining ground over the traditional solutions of Kahn, Doherty and Chireix.
Dr. Cripps obtained his
PhD and master’s
degrees from Cambridge
Since starting work at
Plessey Research Labs in
1974, he has been involved in most aspects of Gallium Arsenide technology and circuit applications. From 1981 he worked in the USA, holding technical and management positions at Watkins Johnson, Loral, and Celeritek. He became an independent consultant
in 1990 and specialized in high efficiency RFIC PA design for mobile phones. He returned to England in 1996, where he has been involved mainly with high power PAs for cellular basestations. His current technical activities are focused on the characterization of memory effects in RF power amplifiers, and the development of advanced loadpull techniques. Dr. Cripps is the author of two books on RF power amplifier design, both of which are listed as best-sellers by Artech House, “RF Power
Amplifiers for Wireless Communications” (1998), and “Advanced Techniques for RF Power Amplifier Design” (2001). He holds five US patents.