Harmonic-Injection Class-EM/F3 Power Amplifier with Finite DC-Feed Inductance

This paper presents the analysis and design of the Class-EM/F3 power amplifier (PA) with finite dc-feed inductance and isolation circuit. When compared to the classical Class-EM PA, the proposed PA offers a significantly lower peak drain voltage. The idealized voltage and current waveforms of the PA show that the main circuit fulfils the ZVS/ZVDS/ZCS/ZCDS conditions, thus minimizing power dissipation during off-to-on (as in the Class-E) and on-to-off (as in the Class-E−1) transitions. Closed-form design equations for the load-network parameters of the PA are derived and the analytical results are confirmed by harmonic-balance simulations. A circuit prototype, employing a transmission-line load-network was designed and implemented using GaN HEMTs. The constructed PA delivered a PAE of 85.4% and a Pout of 41.6 dBm at 1.25 GHz.