Wide Range Switched Mode RF Power Amplifiers and their applications

Abstract

Switched-mode power amplifiers (SMPAs) are desired that can work across a wide range of power levels and load impedances with fast response speed while maintaining high efficiency. Such designs would be valuable for many applications including plasma generation and wireless power transfer. We introduce a new wide-range SMPA architecture that provides direct output voltage modulation, enabling it to modulate output power and compensate for resistive load variations. Dynamic frequency modulation is leveraged to address reactive load variations. The new architecture enables all the semiconductor switches to maintain zero-voltage switching across all operating conditions. Experimental results shows that the wide-range half bridge power amplifier was able to deliver a wide power range of 25 W - 95 W power range across each individual resistive load in the range of 5 Ω - 20 Ω with up to j15 Ω reactance. The maximum dc-ac efficiency is 86 with 20 Ω load and 110.5 W load power.