High-efficiency modes contiguous with class B/J and continuous class F⁻¹ amplifiers

We propose a new formulation for high-efficiency modes of power amplifiers in which both the in-phase and out-of-phase components of the second harmonic of the current are varied, in addition to the second-harmonic component of the voltage. A reduction of the in-phase component of the second harmonic of current allows reduction of the phase difference between the voltage and current waveforms, thereby increasing the power factor and efficiency. Our proposed waveforms offer a continuous design space between the class B/J continuum and continuous F⁻¹ achieving an efficiency of up to 91% in theory but over a wider design space than F⁻¹. These waveforms require a short at third and higher harmonic impedances, which are easier to achieve at higher frequency. The fabricated amplifier using a GaN HEMT CGH40010F achieves 79.7% drain efficiency and 42.2-dBm saturated output power at 2.6 GHz, which gives a frequency weighted efficiency of 92.4%⁴√ GHz with this device.