Harmonic tuned RF/microwave high efficiency power amplifier design accessing the intrinsic drain

A specific design technique of harmonic tuned power amplifiers based on FET device assumption is developed in this paper. The main issue of this methodology is to understand how to access the device's intrinsic drain. Design equations are presented for the distributed output matching networks, which can be used independently of the harmonic tuned amplifier type. In order to validate the presented technique, two hybrid amplifiers have been implemented, the former is a Tuned Load power amplifier and the latter is an inverse Class F one. The superiority of the inverse Class F amplifier, in terms of efficiency, gain and output power, has been demonstrated. The efficiency in saturation of the inverse Class F module reached 70 %, placing this amplifier in the state-of-the-art for amplifiers using GaN-HEMT devices at frequencies close to 2.4-GHz.