Class-E, class-C, and class-F power amplifiers based upon a finite number of harmonics

Class-E operation at UHF and microwave frequencies is achieved by using tra nsmission-line networks to provide the drain harmonic impedances of an idea l class-E power amplifier (PA). This paper develops a technique for analysi s of such amplifiers that are based upon a finite number of harmonies. The technique is generally applicable to classes E, C, and F as well as PAs wit h harmonic reactances not corresponding to those of established classes. Th e analysis shows that the maximum achievable efficiency depends not upon th e class of operation, but upon the number of harmonies employed. For any se t of harmonic reactances, the same maximum efficiency can be achieved by pr oper adjustment of the waveforms and the fundamental-frequency load reactan ce. The power-output capability depends upon the harmonic reactances and is maximum for class F.