High-Efficiency Compact Broadband Power Amplifier Using Seamless Mode Transition within Class-E Subsets

A novel design methodology for a broadband power amplifier (PA) utilizing a mode transition in the Class-E/F continuum is presented. The mode transition is achieved by effectively varying the shunt capacitance, thereby generating variants of Class-E operation mode, namely Class-E/F2 and Class-E/F3. While similar Class-E-based broadband PAs in the literature expanded the design space relying on precise theoretical waveform analysis, the proposed design approach adopts a macroscopic perspective by treating the nominal Class-E amplifier's shunt capacitance CS as a variable. This simplification facilitates a practical way to address the adverse effects of FET parasitics, thereby enabling continuous high-efficiency operation across a wide frequency range. The proposed strategy is validated through a highly compact prototype 1.7-2.3GHz, 10W GaN HEMT PA, achieving over 70% drain efficiency across a 540MHz bandwidth by seamlessly transitioning among three closely related operation modes.