Push–Pull Class Φ2 RF Power Amplifier.

The Class Φ₂/EF₂ amplifier is an attractive topology for high-voltage and high-frequency power conversion because of the high efficiency, reduced device voltage stress, simplicity of gate driving, and load-independent ZVS operation. Due to many degrees of freedom for tuning, previous studies can only solve the single-ended Φ₂ circuit using numerical methods. This work focuses on improving the design and operating characteristics of a push–pull Φ₂ amplifier with a T network connected between the switch nodes, or a PPT Φ₂ amplifier. The PPT Φ₂ amplifier has less circulating energy and achieves higher cutoff frequency ƒ_T than other Φ₂/EF₂ circuits. We, then, present a series-stacked input configuration to reduce the switch voltage stress and improve the efficiency and power density. A compact 6.78-MHz, 100-V, 300-W prototype converter is demonstrated that uses low-cost Si devices and achieves 96% peak total efficiency and maintains above 94.5% drain efficiency across a wide range of voltage and power. Together with the advances in wide-bandgap semiconductors and magnetic materials, the PPT Φ₂ circuit opens more possibilities for the state-of-the-art performance of solid-state RF amplifiers in high-frequency, high-power applications, including wireless charging for electric vehicles, plasma RF drives, and nuclear magnetic resonance spectroscopy. [ABSTRACT FROM AUTHOR]