Design of a harmonically tuned RF Power Amplifier (PA) with enhanced efficiency and gain is presented in this letter. It makes use of a tri-band impedance transformer as a two-port output network for facilitating concurrent optimum fundamental and harmonic impedances at the drain terminal. The design is augmented by analytical formulations and analysis to identify the optimal impedance matching scenario at the fundamental, second harmonic, and third harmonic. A thorough analysis reveals that the proposed PA design scheme is very simple while maintaining the performance obtained from the load-pull. A prototype operating at a frequency of 3.5 GHz is developed on RO5880 using 10W GaN HEMT. An excellent agreement between the measured and the EM simulated results validates the proposed design technique.
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