Multi Module Parallel MHz Power Amplifier with Hybrid Structure and Optimized Control Strategy

Megahertz power amplifiers typically modulate power by paralleled-architectures and outphasing methods. However, when power drops in a large ratio, the effective admittances of modules are always not within the high-efficiency range. This article optimizes four-paralleled-module system through two operation modes: four modules turn-ON at high power and two modules turn-ON at low power to reduce the effective susceptance range at low power. In addition, a combining network consisting of four independently optimized T-networks is proposed to provide ideal load conditions for each module during phase variation. With the help of new networks and hybrid modes, the system is optimized to ensure that the effective admittance trajectory of each module is within the minimum loss range. A 13.56 MHz prototype consisting of four Class E modules is constructed, which maintains an efficiency of 76%–89% with output power of 20–200 W, with an average improvement of 9.5% compared to asymmetric Chireix methods.