Steady-State Simulation and Optimization of Class-E Power Amplifiers With Extended Impedance Method

This paper proposes a new iteration-free steady-state analysis to the Class-E power amplifier (PA) in frequency-domain by extending the scope of electrical impedance. Owning to this extension, the impedances of different circuit components in the Class-E PA circuits, including the active switches, can be expressed in matrix form. Based on the conventional circuit laws, e.g., the series and parallel laws and the Ohm´s law, the steady-state characteristics of a whole Class-E PA circuit can be obtained by vector and matrix manipulation. The number of harmonics involved in the calculation have effects on the computational efficiency and accuracy. The influences of some circuit conditions towards the selection of harmonic number are discussed. The proposed formulation enables fast mapping of some performance indices, e.g., the output power and conversion efficiency, under steady state, so that the changing trends of these indices with respect to the variations of specified circuit parameters can be estimated. This feature can be utilized to carry out offline optimization by tuning some passive components, or online optimization by tuning two in situ adjustable parameters, i.e., the switch driving frequency and duty cycle. The later scheme provides preliminary knowledge on the in situ tuning of Class-E PA in the load varying applications, e.g., electric process heating and wireless power link.