A load modulated balanced amplifier with linear gain response and wide high-efficiency output power back-off region

This paper presents a new mode of operation for load modulated balanced amplifiers that overcomes two limitations of the original technique by providing a linear gain response and a wide power back-off region with high efficiency. Compared to Doherty power amplifiers, this technique still maintains some of the bandwidth advantages and the inherent design simplicity typically associated with the load modulated balanced amplifier. A prototype has been realized and characterized with single-tone measurements. At 1850MHz and 2150 MHz, it shows a maximum output power in excess of 250W, and a power added efficiency greater than 45%, at 9 dB back-off, with a gain variation vs. power of less than 2 dB