Symmetrical class-E_M power ampli er for
very low harmonic-content applications <Abstract> The symmetrical class-E power amplifier achieves low THD (Total Harmonic Distortion) and high output power because of the push-pull configuration. The switch current of the symmetrical class-E power amplifier, however, includes a step change at the switch-turn-off instant, which is a bottleneck of the cost reduction and the power conversion efficiency improvement. This report proposes a novel symmetrical class-E power amplifier. By adding an auxiliary amplifier to the symmetrical class-E power amplifier, the proposed amplifier has no jump on both the switch-voltage and switch-current waveforms. The proposed amplifier can achieve high power conversion efficiency at high frequencies even if the switching speed of the MOSFET is slow, which leads to the cost reduction. Additionally, the output power increases because of the auxiliary circuit. The proposed amplifier is seen as the symmetrical class-EM amplifier. In this report, design curves of the proposed amplifier are given and a design example along with the simulation results is shown. The simulation waveform achieves smooth switching conditions perfectly, which verifies the obtained design curves. Because the THD of the proposed amplifier is almost the same as the symmetrical class-E power amplifier, it can be stated that the proposed amplifier achieves low THD, high output power, and high power conversion efficiency simultaneously with cost reduction. |