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Abstract
This paper presents a broadband high-power amplifier using transmission-line transformers with a high impedance transformation ratio. Two series-connected transformers with 1:8 and 1:1 impedance transformation ratios are used at the load network of a single-balanced high-power amplifier to match the low load impedance in broadband. The same transformer configuration is also used at the input network. A negative feedback is applied to improve the gain flatness and to increase the stability over the broadband. In order to validate the proposed circuit structure, a broadband high-power amplifier is designed and implemented to achieve an output power of more than 400 W in the frequency band of 30 to 500 MHz. The implemented power amplifier exhibits a flat gain response within 1.80 dB at an average of 19.1 dB and high power-added efficiencies of 28.0
to 56.9
at an output power of 400 W over the entire frequency band.
Acknowledgments
This work was supported by the National Research Foundation of Korea under Grant 2012-003485.