Wideband Class Φ2 Power Amplifier for HF Applications

For high-frequency dc-to-RF power conversion, the Class Φ2 is a switch-mode power amplifier (PA) topology capable of achieving low device voltage stress while utilizing simple gate driving. The challenge with common switch-mode PA circuits is that they are narrowband, with the output power and efficiency degrading outside the nominal operating point. In applications such as plasma generation and wireless broadcasting, the PA is required to be efficient with constant gain across broadband. To enable the Class Φ2 for wideband operation, we incorporate a phase-switched impedance modulation (PSIM) variable capacitor and a reactance compensation network. This work experimentally demonstrates a 300 W PA prototype from 12.56–18.06MHz with 93% peak drain efficiency.