Effect of Bias Condition and Input Harmonic Termination on High Efficiency Inverse Class-F Amplifiers

The optimization of the operating bias condition and input harmonic termination is investigated for the practical circuit design of high efficiency inverse class-F amplifiers. It is found that inverse class-F amplifiers exhibit a high efficiency at the quiescent current of larger than 10% Idss, which cannot be achieved by class-F amplifiers. It is also revealed that the efficiency of inverse class-F amplifiers can be effectively improved by the open or high impedance of the input 2nd harmonic termination. These results have been explained by the behavior of the amplitude and phase relationship between the input and output harmonics.