The Load-Modulated Balanced Amplifier
Date/Time: Oct 23, 2018 | 9 a.m. PT/12 p.m. ET/ 4 p.m. UTC
Presented by: Dr. Steve C. Cripps Professor, Cardiff University
Hosted by: National Instruments
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Quadrature-balanced amplifiers hold a revered position in the historical development of broadband microwave amplifiers up to 20 GHz and beyond because they replaced unreliable traveling wave tubes (TWTs) with solid-state equivalents. After declining in popularity when monolithic microwave integrated circuits (MMICs) entered the market, they are now becoming useful again due to research at Cardiff and University of Colorado, Boulder showing a surprising and counter-intuitive property that allows active load modulation of the output match presented to the balanced transistors. This has enabled broadband matching network design to break away from conventional constraints and has opened up application avenues in high efficiency RF power amplifier (RFPA) design, both in telecommunication and electronic countermeasure (ECM) bands.
Dr. Steve C. Cripps obtained his master’s and Ph.D. degrees from Cambridge University in the 1970s. After working for several years with the pioneering gallium arsenide (GaAs) group at Plessey Research, he emigrated to the U.S., where he worked for 15 years in various engineering and management positions at Watkins Johnson, Loral, and Celeritek. In 1996 Dr. Cripps returned to the UK, working as an independent consultant before taking on an academic post at Cardiff University, where he is currently a distinguished research professor. Dr. Cripps has authored several best-selling books on RFPA design and is a regular contributor to the IEEE Microwave Magazine with his popular “Microwave Bytes” column. Dr. Cripps is an IEEE Fellow was the 2008 recipient of the IEEE Microwave Application Award.